Monitoring a Hydronic Heating System?

I am finally installing a new diesel heating system which will be installed in parallel with my current heat pumps. It consists of an Olympia 105 Boiler and 3 zones With Real fan units, an everhot system and water tank loop. The unit will be controlled by a Nest thermostat with solenoids to turn off heating loops in the case of just wanting hot water.
Has anyone done more advanced monitoring of a system like this? I am thinking about the following but open to ideas. I use Maretron for most monitoring.
1. Pressure (monitored on the hot side manifold)
2. Output temp (monitored on the hot side manifold)
3. (Three) Return temp (monitored on each return leg right before the return manifold)
4. Run/Power Indicators on the pump/boiler and solenoids.

Anything I’m missing or you would do differently?
Thanks
AC

When I was setting up my Connecticut home's "hydronic" heating system for unattended use for the winter months when we are in Florida, the HVAC contractor recommended a low water shutdown in addition to the presumably code mandated fire shutdown above it.

He said that all hydronic systems leak and if the water level dropped too far (Our potable water was shut down and drained. Normally the city water pressure would make up any leakage.) the boiler's burner could melt the internals and cause a fire. All it took was a simple level sensor wired to the burner shutdown.

So I would add a fire shutdown to mitigate a catastrophic situation and a low water shutdown to prevent the fire. These are not just monitors as they automatically shut the burner down without human intervention.

David

AC
Sounds like a decent system. I like your choice of Real heat exchangers. Do you have an engine coolant HXer to heat the coolant when cruising to allow the boiler to remain off but rest of hydronic system on?

Regarding your four questions. To me, items 2 and 3 are well addressed by correct placement of aquastats. Since these, in conjunction with thermostats, control the on off of the HXers and the cycling of the boiler I'm hard pressed to see the need for coolant temperature monitoring. You could always use an IR gun to assess if a temperature sensor or two would yield useful data.

Regarding pressure, it may prove useful to assess pump health or aging coolant. Is your pump variable speed? If not, pressure is just data with no control available. Then the question as to where do you install the pressure sensor? My pump never wore out but after 12 years I replaced it "just in case" and now have a running takeout spare. Coolant aging, maybe a change every 5 years or so much like engine coolant on a time basis.

My Hurricane has a fault description monitor by the boiler (another could be mounted elsewhere) as well as a status gauge as to boiler on off, cycling and system off. My Hurricane is better monitored than the three ACs and furnaces I have in my dirt home which utilize nothing more than a standard Honeywell unit.

Bottom line, possibly be conservative and start out with standard setup as per Olympia and installer recommendations. You can always add stuff later if the need arises. Often, additional monitors and instrumentation are the weak, frustrating or puzzling points.

I think the system has both fire and low fluid shut downs but will check.

Sunchaser,
Normally I’d agree but the installer was saying draining the system is a pain to add anything and my biggest concern is remote monitoring since I’ll use this when it’s super cold or to heat it up before I arrive for the weekend.

Arthurc said:

I think the system has both fire and low fluid shut downs but will check.

Sunchaser,
Normally I’d agree but the installer was saying draining the system is a pain to add anything and my biggest concern is remote monitoring since I’ll use this when it’s super cold or to heat it up before I arrive for the weekend.

Click to expand...

There are some really neat marine remote sensing systems out there. Did you have a specific one in mind? I've a friend who keeps his vessel in Petersburg AK and monitors his critical data from the SE US. Regarding your heating system, temperature monitors and flow on/off sensing can be externally mounted.

I'm using Maretron with the cloud monitoring but also a separate linux box that scrapes n2k data and puts it in a time series db, that tends to be the most immediate in terms of alerts on the system.

sunchaser said:

There are some really neat marine remote sensing systems out there. Did you have a specific one in mind? I've a friend who keeps his vessel in Petersburg AK and monitors his critical data from the SE US. Regarding your heating system, temperature monitors and flow on/off sensing can be externally mounted.

Click to expand...

Do you have some examples of external monitoring options?

A really large accumulator might add make up water / antifreeze mix if you actually have a fluid loss over time.

I'm in the process of building my second Olympia-based, real heater-base system, and can share what I'm doing differently. The changes aren't necessarily because there was a problem with the first system, but I can't help myself trying to make improvements. I'll mention where I think there is something that will really matter to you, but otherwise just take it for general consideration and entertainment.


- I agree with Sunchaser that measuring loop temp, especially in multiple places, is really more of a design verification exercise rather than on going monitoring. So I definitely wouldn't install multiple sensors. However I do plan to install one on the supply side manifold. I don't think there is huge value in it, but I plan to anyway. I'm also curious to see how the loop temp holds up when running off engine heat, but that is arguably a one-time design verification check.


- I will install a pressure sensor, and recommend it, mostly to monitor for leaks. Even if the system has a shut down, which I agree it should, I want to know when a leak is happening, not after it has happened. I agree that leaks can and probably will develop at times over the life of the system, but those are faults that should be corrected. A properly operating system should lose no fluid. None, zip, zilch, nada. If it is losing some, I want to know right away.


- Setting up to run off waste engine heat while underway is a wonderful thing, so I highly recommend it if at all practical.


- My last system has no automatic zone valves, so hot water circulated through all the loops whenever the circulator was running. There were manual valves so I could shut off everything except the HW in the summer, but it was manual. Up to a point I think this approach is fine, but on the new system I am building it the way a home system is done with automatic zone valves that are responsive to the thermostats. This better directs the heat where you want it, when you want it. It may be overkill, but I did it anyway. But this was prompted by a particular issue, so read on....


- I encountered an interesting phenomenon on my last system, and it's what prompted me to use zone valves on the new system. One loop ran through the HW tank to head domestic hot water from the boiler. That was all good. However when at dock and on shore power, I used the electric HW heat. Now if the heat demand from the living space was light, the boiler would cool down between runs, and when it would start up, the water flowing through the HW heater would actually draw heat out of the HW tank rather than put heat in. The electric HW would kick on, and I was effectively heating the boat with electric, at least to some degree. So at a minimum I wanted a zone valve to only direct water through the HW tank when there was actually a call for heat from it. This whole thing wasn't the end of the world, but I decided to improve on it in the next system.


- I am planning on monitoring the burner on/off time in one way or another. They may have changed it, but on the last SureWire control box the hour meter ran whenever there was power to the system, not burner run time. So it measured breaker-on time, which was always, and totally useless. This time I want a meter that counts burner run time. That's what drives maintenance, so that's what I want to monitor. Now the new SureWire box is quite different, and I don't know yet whether the hour meter function has changed, but I'm not using the SureWire box, so haven't pursued it. A call to them would probably answer the question. I plan to either install an hour meter, or monitor and count run time with Maretron.



- On a refit it might not be an option, but I have insulated my PEX heating loops. And many people prefer not to insulate them because they indirectly bring heat to other parts of the boat. A friend is building an identical boat to mine (as much as any two Nordhavn's are the same - not) and he has elected not to insulate. So people go both ways.


- Many boats, like my last one, are built with a header tank to maintain water pressure. This time around I am building a closed system with an expansion tank, as you would build a home system. This eliminates the need for a tank at the highest point in the system, and gives a little more control over pressure.


- For monitoring, I think room temp is the most important thing to monitor. That will tell you whether the heat is working, or if you have a problem that needs to be tended to right away. I left our heat on all the time, just as I do at home. When we were away from the boat I just turned the temp down. That protected against freezing, and left a more approachable boat when we returned.

Arthurc said:

Do you have some examples of external monitoring options?

Click to expand...

There are many sources of external monitoring of small pipe flows and temperature. Grainger has many aqua stat choices. Or go to Keyence for flow switches and Kele for temperature monitoring using Q strap mini or the strap on Precon sensor. Our circulating pump is positive displacement so flow on off is more important to us than volume.

As TT mentioned in his post, there are several ways to hook up and modulate the use of hydronic for water heating and utilizing off engine heat. Since we have twins, we use one engine for heating the hot water tank and the other, utilizing a plate heat exchanger, for heating the hydronic system when underway. We have no need to plumb the hydronic system into the hot water tank but the option is always there.

After 13 years of operation the various aqua-stat performance has been flawless. The only leaks we've had in our system have been with the ITR HXers, which were picked up by monitoring paper towels placed under the units.

I have been using a product from BAYweb. It's a web enabled thermostat with additional digital inputs and outputs. All temperature and operation of the boiler is available through a web portal, just keep the boat network connected to the Internet. It also supports X10 and wireless sensors, so I have a motion alarm and companion way switch. Also, I put in an AC coil relay to give dry contact open when shore power is disconnected. It can notify through text or email.


Bonus, no recurring charges for the web portal, and I have a digital thermostat for the furnace. I installed in 2011 and it works great. It's marketed as HVAC cloud control for buildings. The cloud portal has graphs and operation details, along with alarm events. It works well for the remote monitoring part and is handy from down below when I can use the phone to turn down the heat. I only have one zone. Check it out...



www.bayweb.com

twistedtree said:

I'm in the process of building my second Olympia-based, real heater-base system, and can share what I'm doing differently. The changes aren't necessarily because there was a problem with the first system, but I can't help myself trying to make improvements. I'll mention where I think there is something that will really matter to you, but otherwise just take it for general consideration and entertainment.

Click to expand...

Very helpful, thank you! A few comments.

1. I too will be using the engine to heat the loop so like the idea of a monitor for temp there (plus im a bit of a nerd when it comes to monitoring stuff), the time series db I store my n2k sentences in makes it really interesting to try and understand correlations and later build in custom monitoring... just no time for that now.

2. I won't have automatic zone valves but will have solenoids on each zone so I can control them however I choose, for now its just going to be switches in the salon next to the Nest. Each Real heat exchanger will use a 12v temperature fan controller versus the standard high/low/off switch, this should allow me to hold more precise temp in each cabin.

3. Very interesting on the hot water issue with electric heating the system, ill keep that in mind. I have heat pumps as well so it would be rare that im on shore power, using this system versus the CruisAirs.

4. Love the idea of actual boiler fire time, will ask the installer today.

5. Im confused on Expansion tank versus Header Tank. I have an expansion tank being installed but the installer still wanted it as the highest point in the system. Is there some other type of expansion tank?

6. Agree on room temp, I have a TMP100 which will be dedicated to all the staterooms, just need to take the time to install it.

Thanks!

Arthurc said:

..............


5. Im confused on Expansion tank versus Header Tank. I have an expansion tank being installed but the installer still wanted it as the highest point in the system. Is there some other type of expansion tank?

.............

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I've had an Olympia boiler with expansion tank and Hurricane system with a header tank, both systems the tanks were at a low point below the air handlers.

On the Olympia system the installer used Spirovent automatic air bleeders on the outlet side of the boiler at the top of the expansion tank as well as manual bleed valves at each air handler. There was room on that boat for make up tank and pump to keep the system topped up.

On the Hurricane system the installer used Caleffi automatic air vents at high points. If the lines went down from an air handler then back up to the next it got a Caleffi. In addition to the expansion tank there is an overflow bottle similar to the overflow bottle in a car or truck.

The Caleffis take more fiddling to get the air out, opening the manual valve. Both take a while as in multiple startups with full cool downs to get all of the air out. But once cleared out are trouble free.

Installation manuals will say never put the expansion tank or the header tank at a low point but it works. The Olympia system worked for many years without trouble. The Hurricane installation is relatively new but as far as air in the system is fine. There are other issues related to the quality of the Hurricane and the installation work but that's another story.

Portage_Bay said:

I've had an Olympia boiler with expansion tank and Hurricane system with a header tank, both systems the tanks were at a low point below the air handlers.

On the Olympia system the installer used Spirovent automatic air bleeders on the outlet side of the boiler at the top of the expansion tank as well as manual bleed valves at each air handler. There was room on that boat for make up tank and pump to keep the system topped up.

On the Hurricane system the installer used Caleffi automatic air vents at high points. If the lines went down from an air handler then back up to the next it got a Caleffi. In addition to the expansion tank there is an overflow bottle similar to the overflow bottle in a car or truck.

The Caleffis take more fiddling to get the air out, opening the manual valve. Both take a while as in multiple startups with full cool downs to get all of the air out. But once cleared out are trouble free.

Installation manuals will say never put the expansion tank or the header tank at a low point but it works. The Olympia system worked for many years without trouble. The Hurricane installation is relatively new but as far as air in the system is fine. There are other issues related to the quality of the Hurricane and the installation work but that's another story.

Click to expand...

To expound on the difference, when I refer to an "expansion" tank, I mean a tank with air air bladder that gets pre-charged with air. The hydronic glycol is then pressurized to partly fill the tank, squishing the air bladder a bit. Glycol expansion then just squishes the bladder a bit more. It's just like an expansion tank or accumulator in a water system.


What Sure Marine sells doesn't contain a bladder and doesn't get pre-charged in any way. It's just a tank partly filled with glycol up high somewhere. System pressure at the boiler is whatever the head of the tank is. A tank 10' above the boiler will give about 5 psi of pressure, where a bladder expansion tank will run around 15 psi. The header tank may have a pressure cap like on a radiator (mine did) and it might pressurize a bit as the glycol expands, but the baseline pressure will be the head of the tank.


I didn't have any problems with the header tank on my last system, but didn't want to have to plumb up to the fly bridge for a header tank. And with a zoned system, you need to be sure everything is open to the tank on one end of the loop or the other so it can expand. It was simpler to just install a pressurized expansion tank next to the boiler.

What are the solenoid valves that you are using?


For zone valves, I'm using Taco Sentry valves. They nominally work off 24VAC, but confirmed with Taco that they would work fine off 24VDC as well, though it's not a tested and supported use. I rigged up a test and ran one through 7600 cycles and it worked fine, so that's what I'm doing. Otherwise a 120V to 24V transformer is needed. This way my control system and fans are all 24VDC, and only the circulator and boiler itself are 120VAC.

Can't add much from a boating standpoint, but as far as zone solenoid vavles, here are a couple of points:

They are likely to need to be replaced.
They are likely to leak over their life at the shaft seal.

As a result:

Mount them in an area where they are easily worked on and the leak won't damage anything. While it might require a great deal more piping, all of them should be located together in the mechanical room with a manifold configuration.

Also, they should be setup with a double block and bleed. Simply, a valve before and after to isolate and unions or flanges to facilitate removal and replacement. Ideally, a shaft seal failure can then be isolated to allow the system to still be utilized, and flanges or unions to facilitate a quick replacement with an already setup spare. While all of this will significantly increase plumbing costs, it greatly enhances overall system reliability by being able to isolate a failure point.

Ted

twistedtree I agree with your definition of an expansion tank. A tank with an air bladder. They serve as a 'buffer' to handle expansion and contraction as the glycol expands and contracts.

To clarify so we're all speaking the same language. As used in a heating system.

Header tank.
A header tank doesn't have an air bladder and will very likely have a radiator style cap and works best with an overflow bottle. As the glycol heats up and expands the radiator cap spills the overflow into the overflow bottle. As the glycol cools and contracts the excess is sucked back into the header tank. Very like your car or truck's radiator and overflow bottle.

A properly set up hydronic system needs an expansion tank or header tank or both. Ideally they should be the highest point in the system to capture entrained air. But if not and you are very careful about filling, bleeding and maintaining the system you can put the expansion tank and or header tank lower in the system. Spirovent or Caleffi type automatic air vents help with this.

Air handler.
An air handler is the kind of thing Sure Marine or ITR Hurricane sells. It has a copper coil the glycol flows through with fins and a fan. It used to heat the room.

Heat exchanger.
A heat exchanger can be a shell and tube exchnger or flat plate exchanger. It may be used to capture waste heat from the engine for use in the hydronic sytem. Or to heat the domestic water heater, best to not have engine ethylene glycol near potable water.

And of course we've all seen variations on the above....

Portage_Bay said:

twistedtree I agree with your definition of an expansion tank. A tank with an air bladder. They serve as a 'buffer' to handle expansion and contraction as the glycol expands and contracts.

To clarify so we're all speaking the same language. As used in a heating system.

Header tank.
A header tank doesn't have an air bladder and will very likely have a radiator style cap and works best with an overflow bottle. As the glycol heats up and expands the radiator cap spills the overflow into the overflow bottle. As the glycol cools and contracts the excess is sucked back into the header tank. Very like your car or truck's radiator and overflow bottle.

A properly set up hydronic system needs an expansion tank or header tank or both. Ideally they should be the highest point in the system to capture entrained air. But if not and you are very careful about filling, bleeding and maintaining the system you can put the expansion tank and or header tank lower in the system. Spirovent or Caleffi type automatic air vents help with this.

Air handler.
An air handler is the kind of thing Sure Marine or ITR Hurricane sells. It has a copper coil the glycol flows through with fins and a fan. It used to heat the room.

Heat exchanger.
A heat exchanger can be a shell and tube exchnger or flat plate exchanger. It may be used to capture waste heat from the engine for use in the hydronic sytem. Or to heat the domestic water heater, best to not have engine ethylene glycol near potable water.

And of course we've all seen variations on the above....

Click to expand...

Very helpful. Have not yet decided on the solenoid valves, im using some basic 12v ones from Amazon (about 50 bucks each) on my water system for things like water maker flush without issues but they likely have less than 100 cycles on them so far and replacing is easy.

OC, good call on the valves on both sides of the solenoid!

TT, what specific expansion tank are you using? I like that idea much better. Any maintenance needed?

AC

Arthurc said:

Do you have some examples of external monitoring options?

Click to expand...

The photo is real time. I am 120 miles from my boat.
I monitor all critical systems, and control heating either automatically or manually.

smartthings.com

"Setting up to run off waste engine heat while underway is a wonderful thing, so I highly recommend it if at all practical."


Also if you set-up the heating system to keep the engine coolant / engine
warm when not underway you will always have warm coolant = engine.

All of our tugs are set-up this way, engines are always around 120 -130F
even when tied-up for extended periods.

TT,
Just heard back from the installer, he like the expansion tanks but doesn't like that they don't allow for an easy fill point should a small leak occur, thoughts? How are you handling that?
AC

Arthurc said:

TT,
Just heard back from the installer, he like the expansion tanks but doesn't like that they don't allow for an easy fill point should a small leak occur, thoughts? How are you handling that?
AC

Click to expand...

The tank is Amtrol/Extrol. Model EX15. Maintenance is just periodically checking the air pressure and checking for leaks. They do have a finite life, so plumb a shutoff valve. I just changed one on a land system yesterday that was about 12 years old.


I have always done filling and flushing via a pump and service valves at the boiler. The boiler will (or should) have a drain valve with a garden hose fitting. I have also used Webstone's flange/service valves on either side of the circulator pump. You can fill on one side and drain back to a container on the other side. Pump glycol through like that drawing from and returning to a bucket. It will fill and purge the system quite nicely. Use your zone/loop valves to push fluid through one loop at a time to bleed them out. As long as the water is moving fast enough all the air will come along with it. You should check individual air bleeds after, but I think you will find little to no air in the system. I have done this with multiple systems with loops and radiators that run a good 10-12 above the boiler, and it has worked well. Also, install a spirovent and an air separator in conjunction with the expansion tank. That will help get out an residual air.


Interesting idea on the solenoid valves, but it begs the question why heating systems use zone valves, and not the solenoid valves like you describe. I don't know why, but would guess there is a reason. Perhaps temp rating? Perhaps opening and closing more slowly is better? Perhaps the supported flow rate? I think it warrants a close look.

Good points on the solenoid, when I looked before they seem to be a good solution, they have a flow rate of about 7gpm, a max temp of over 200 degrees and a max pressure of about 100psi.
I would bet that its the fast acting nature of solenoid valves, its likely to cause a water hammer effect. Im not sure if that's a big issue for me since its all pex and I would never be turning off the flow, just cutting off various zones. The one that goes to the engine exchanger will always be on.

Here's the Webstone valve I was talking about. I forgot to include the link.


https://www.supplyhouse.com/sh/control/product/~product_id=40416


Pick the size that best matches.

You guys are making my head spin with all this tech talk.

We have a Webasto hydronic system and have it turned on from late Fall to early Spring. I have to move fuel to keep the boat level every now and then but really like the idea of being able to monitor for pressure leaks. At this point I check the bilges for leaks in the system.

If I were ever in the position to order a new boat, the systems you are talking about would be on the hit list.

Is it practical to plumb everything off the water heater - assuming a large unit with multiple HEX coils?

- water heater has its internal electric elements
- engine coolant plumbed to WH to heat it through a HEX
- diesel furnace sends its water to the WH (either potable water directly or antifreeze through a HEX)
- a closed loop of antifreeze circulates to all the cabin heaters, fed from the WH

Therefore you now have three different sources of heat.

w8n4sun said:

You guys are making my head spin with all this tech talk.

We have a Webasto hydronic system and have it turned on from late Fall to early Spring. I have to move fuel to keep the boat level every now and then but really like the idea of being able to monitor for pressure leaks. At this point I check the bilges for leaks in the system.

If I were ever in the position to order a new boat, the systems you are talking about would be on the hit list.

Click to expand...

Everything is relative.
I'm a coastal cruiser with some redundancy and generally avoid freezing temperatures. As you venture into more remote areas and outside air temperature can be life threatening, the need to keep a system functioning at some level becomes more critical. The concept of being able to isolate a failed component or recognize a failing component before it generates a larger problem justifies some added complexity. If all you have to do is make it to the next marina, well maybe not so important.

Ted

makobuilders said:

Is it practical to plumb everything off the water heater - assuming a large unit with multiple HEX coils?

- water heater has its internal electric elements
- engine coolant plumbed to WH to heat it through a HEX
- diesel furnace sends its water to the WH (either potable water directly or antifreeze through a HEX)
- a closed loop of antifreeze circulates to all the cabin heaters, fed from the WH

Therefore you now have three different sources of heat.

Click to expand...

I think you could, but it may not perform as hoped.


With heat for the living space drawn off the HW tank, you would be compromising the amount and temp of your HW supply.


And with a typical HW electric heating element of 1 to maybe 3kw, that would be the limit of the heat available to worm the living space. In contrast, a boiler is anywhere from maybe 8kw for a small one, to 30kw for the one Arthur is using.

Agreed, you might be able to get a bit of hot air out of a salon fan unit but certainly not the whole boat. Im going oversized for mine, the Oly 60 could work and its about 18kw I think, so 1-3kw is barely going to cut it for localized heat and likely not worth the install pain and the strain it puts on the water heater. As much as possible we are designing to prevent the system from sucking heat from the water heater.