Diesel heater: want to tie it into my diesel tanks

[Jeff F]

Most of us with big tanks or summer cruising plans or tropical destinations are not real concerned with the heater draining our tanks. In which case T’d into the main line will work just fine. While it’s not the best practice it is extremely low risk.

That's what I do. But if I was running a Chinese unit like the OP I would start losing sleep over it.

As discussed above, I think there is a lot more to the dedicated line than the dip tube. Reserve is incidental to the reason it's best practice, I think. I always try to understand the requirement before deliberately ignoring it

My furnace specifically warns against drawing off the engine fuel line. I could say that it's worked fine for five years, but providing a dedicated line is on my list of improvements to harden up systems. I don't really think we should defend it just because it's common practice.

 

[GrandWood]

I came across this little unit, and think it would work just fine to xfer fuel from main line to day tanks. I like the idea of being able to open valve at a tee in mainline, pump the day tanks full and then shut it off. I’m going to install a shut off valve after the tee, and a filter after the pump. Thinking I’ll put the tee right after the racors. And have a valve right at the end of the fill line where the day tanks are.

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[Jeff F]

I don't think there is any requirement to filter fuel for the furnace. You want a transfer pump, something like this, and there's no need for anything other than light-duty hose to the day tank. I'd tap in on the tank side of the fuel filters somewhere.

Amazon.com

 

[SteveK]

I don't think there is any requirement to filter fuel for the furnace. You want a transfer pump, something like this, and there's no need for anything other than light-duty hose to the day tank. I'd tap in on the tank side of the fuel filters somewhere.

Amazon.com

For crying out loud Jeff, he is drawing fuel from the bottom of the tank.

 

[Bmarler]

I like the idea of pulling after the racors. It’s always best to burn filtered fuel.
Any of those small cheap pumps work well for transferring small amounts of fuel, but use a momentary push button or toggle to do it. If you use a maintained switch I guarantee you’ll overfill it at one time or another.

 

[Marco Flamingo]

Hmm. Let's compare and contrast the two solutions.

Day tank pluses:
- limits fuel spill in case of furnace leak/failure
- does not in any way jeopardize fuel delivery to main engine.

Day tank negatives
- when empty needs to be refilled by opening valve, activating pump and closing valve

Tee into main line pluses:
- no need to manage day tank

Tee into main negatives:
- Furnace leak could drain tank(s) into bilge
- furnace leak could stop main engine
- eliminating these risks involves changing valve each time using furnace

The fact that you've never encountered the negatives does not mean they don't exist. I know which option I'd pick to satisfy the simple and safe criteria.

ETA: the third option is for the furnace to draw directly from the tank. This maintains the integrity of the engine fuel system, so would be the appropriate choice if eliminating the day tank.

Seems to me that just putting in a system that doesn't leak is the answer. Mine was first installed by the PO. According to the log, that was in 1991. Almost 10,000 engine hours ago. Don't know how many heater hours, but enough to kill the Webasto. It wasn't until operator error (me closing both tanks), that I learned that Racor filters are the likely suspect in a high vacuum situation. If I was concerned that I would do this regularly, I could put in a one-way valve for $14. Sure would be easier and cheaper than drilling a hole into a main tank (a non-starter for me). I suppose one could buy several of the one-way valves and put them all over the fuel system. Belt, suspenders, thumbtacks, superglue, etc. The need hasn't been indicated in 36 years in my system.

If somebody feels the need for using the day tank kit that comes with diesel heaters, be aware that you shouldn't install the tank in the engine room. Even the Racor fuel filters now have a fire shield on the plastic bowls. I don't think a plastic day tank would pass ABYC. Also, if you use a pump, like a little fuel pump, to fill a day tank, do not put a switch where somebody (you or a guest) could activate it accidentally. Especially true if using the pump listed above (1.5 gallons per minute). I can (and have) quickly addressed air in the fuel lines. I haven't had to address overflowing 4 gallons of diesel into the bilge. I would prefer the former.

I have many connections in my fuel system that I could worry about. Two big tanks, both with valves that could fail, I suppose. 3 Racor filters (that have dripped after filter changes.) Valves that allow me to switch between tanks and filters. A fuel pump that allows me to polish the fuel, transfer between tanks, fill the Racors when changing filters, pressurize the fuel line when changing the secondary filters (or refilling the fuel lines from accidental air intrusion.) Counting the secondary filters and connections, there must be +30 "leak" possibilities in my fuel line. Plus, a vacuum gauge T (with the gauge in the engine room). I'm planning on moving the gauge to the helm even though that will require an additional connection (aka, potential leak). I've always thought of the gauge as measuring the potential for air intrusion caused by excessive vacuum, but I guess some would claim that T'ing in the gauge is likely to be the source of air intrusion. From a convenience, safety, expense viewpoint, for me a T for the vacuum gauge, like my fuel filters, polishing pump, heater, etc., is a concern that is easily addressed.

If one is worried about their ability to make quality fuel line connections, a day tank won't save you.

 

[Jeff F]

If one is worried about their ability to make quality fuel line connections, a day tank won't save you.

Having a day tank essentially eliminates the requirement to make quality fuel line connections. Attempting to bring a cheap furnace up to those standards isn't a trivial exercise. Your system is only as strong as the weakest connection.

It may work for you, but there's no way you can convince me that it's a best practice.

 

[Jeff F]

It’s always best to burn filtered fuel.

Agreed. With a day tank I think it's common to incorporate a filter between the tank and the heater. There could be one there now.

My only objection to drawing from the engine side of the Racor is that this is typically where the highest vacuum in the system exists when the engine is running. But I guess since it's only turned on to fill the day tank this is a minor objection.

 

[Jeff F]

Agreed. With a day tank I think it's common to incorporate a filter between the tank and the heater. There could be one there now.

My only objection to drawing from the engine side of the Racor is that this is typically where the highest vacuum in the system exists when the engine is running. But I guess since it's only turned on to fill the day tank this is a minor objection.

I should add that protection against dirty fuel wouldn't be a top priority for me with these heaters, given the ease of replacement. My sense is that they're used all over the world, often with dodgy fuel. We're not talking about protecting an engine here. A $300 heater is hardly an expensive high precision device that needs ultimate protection.

 

[luna]

$300 for a heater, thats outrageous!
Vevor, one of those quality manufacturers from the PRC has an 8 kW unit c/w tank, LCD display, a remote, bluetooth, all the plumbing and ducting allowed for $90 + tax. You might want to buy 3 units so you won't get too cold down the road.

Meanwhile my Eberspaercher D16, (16 kW) now nearing 20 years old that sits behind a large 10 micron filter, has costed me next to nothing for parts. Just a nozzle and the coil for the fuel valve.

 

[Delta Riverat]

There are no 8 kW Chinese heaters. Two and five. The 8's are a relabeled 5. Yeah $100 a throw -

Must be the tariffs.

 

[luna]

You would think that if the claims of 8 kW are fictitious, someone in the litigious US of A would have started an action.
Maybe they have.
Or maybe the manufacturer is playing games with the ratings. Most boilers have an input power rating. 8 kW of input power (in the fuel) likely yields close to 5 kW of output power. The rest goes out the exhaust.

Best to just ignore the ratings and plan to use 2 or more units to heat your 40' boat, here in the PNW. Or better yet, get a real heater.

 

[Jeff F]

You would think that if the claims of 8 kW are fictitious, someone in the litigious US of A would have started an action.

Who are they going to sue? A local online sales entrepreneur who bought a container load from some unknown foreign manufacturer?

Hard to find deep pockets, I suspect.

 

[SteveK]

The Webasto stopped running/starting last spring. Still looking for a fix. Meanwhile I got a Vevor 5KW which mounted into the Webasto bracket and uses same exhaust. Had to change fuel pump as different size needed. Works great. Got it for $135. I see Vevor lists $134 and amazon $142 for the 8KW.

The Webasto fan was found not working, so I fixed that, replacement $600. Fuel pump and glow plug both work but not from the control box replacement $700. Bought a glow plug for $60. New was about $2,500.

Should be cold enough end of November to test out the 5KW, maybe I will get the 8KW as a backup spare $142. With mount and thru hull it will be $200. (thinking maybe I need 2 heaters)

 

[GrandWood]

Every couple of days I burn my webasto full blast to blow out the build up, and for sure you can see the black soot on the dock. I keep temps 65-68, much of the winter I keep a hoodie on while in the boat. I have one of those little buddy propane heaters for back up or just in case it gets real cold.

 

[Portage_Bay]

Every couple of days I burn my webasto full blast to blow out the build up, and for sure you can see the black soot on the dock. I keep temps 65-68, much of the winter I keep a hoodie on while in the boat. I have one of those little buddy propane heaters for back up or just in case it gets real cold.

Be careful with the little buddy heaters. During one winter while living aboard and the boat's heating system was not up to the task I used a little buddy at times. One particularly cold day I had it on full blast. When I wanted to turn it down the knob was frozen and would not move. I'm guessing moisture in the propane froze the valve. I took it out onto the dock and tipped it over to trigger the safety shut off, that worked.

 

[Marco Flamingo]

Be careful with the little buddy heaters.

Also, like cooking with propane, they put out a surprising amount of moisture. When trying to warm things up, one is reluctant to open several windows and get cross ventilation. You will notice it first on windows, but there are other cold surfaces on which the water vapor will condense. Like under seat cushions. High humidity and luke warm heat is the favorite condition for mildew.

Dry heat, and too much of it, is what is needed for liveaboard in the PNW. Diesel heat (or electric when shorepower is available) is really nice. Having too much allows one to open windows. On a boat, the living space is way smaller than a house. Showers, washing dishes, even just breathing can raise humidity onboard.

The little diesel heaters (usually rated at 5 or 8kw) are quite effective, but can be difficult to install in a manner that takes full advantage. Routing ducts to heat 2,3, or 4 areas with a single heater cuts down on efficiency, especially if routed through unconditioned space. One way to get by is to heat one area and use 12V computer fans to move the heated air to other areas. When I intstalled new LED lights, they each had a USB port on them. Little USB fans are also a way to move air around. Can be more efficient and effective than using the ducting that ships with the heater.

 

[mvweebles]

Be careful with the little buddy heaters. During one winter while living aboard and the boat's heating system was not up to the task I used a little buddy at times. One particularly cold day I had it on full blast. When I wanted to turn it down the knob was frozen and would not move. I'm guessing moisture in the propane froze the valve. I took it out onto the dock and tipped it over to trigger the safety shut off, that worked.

I use one occasionally at my cabin in the mountains of Colorado and have had the same problem. Never occured to me it had frozen - makes sense.

Peter

 

[GrandWood]

Also, like cooking with propane, they put out a surprising amount of moisture. When trying to warm things up, one is reluctant to open several windows and get cross ventilation. You will notice it first on windows, but there are other cold surfaces on which the water vapor will condense. Like under seat cushions. High humidity and luke warm heat is the favorite condition for mildew.

Dry heat, and too much of it, is what is needed for liveaboard in the PNW. Diesel heat (or electric when shorepower is available) is really nice. Having too much allows one to open windows. On a boat, the living space is way smaller than a house. Showers, washing dishes, even just breathing can raise humidity onboard.

The little diesel heaters (usually rated at 5 or 8kw) are quite effective, but can be difficult to install in a manner that takes full advantage. Routing ducts to heat 2,3, or 4 areas with a single heater cuts down on efficiency, especially if routed through unconditioned space. One way to get by is to heat one area and use 12V computer fans to move the heated air to other areas. When I intstalled new LED lights, they each had a USB port on them. Little USB fans are also a way to move air around. Can be more efficient and effective than using the ducting that ships with the heater.

Moisture is a problem on my boat, and yes behind the seat cushions in the saloon is the worst, just 3/4 inch plywood walls. When not in use I keep the cushions away from the walls. It’s mostly a problem when it gets real humid outside, like here in pnw all the rain. I’m thinking I will get another diesel heater, try one of the cheap Chinese options, as the single webasto keeps the berths nice and warm, but the saloon on a GB with all the windows, it just can’t keep up. I can crank up the heat on the webasto to wear it will knock the chill outta the saloon, but then the berths are a bit to warm. 68F in the berths results in 60f in the saloon.

 

[GrandWood]

Also, like cooking with propane, they put out a surprising amount of moisture. When trying to warm things up, one is reluctant to open several windows and get cross ventilation. You will notice it first on windows, but there are other cold surfaces on which the water vapor will condense. Like under seat cushions. High humidity and luke warm heat is the favorite condition for mildew.

Dry heat, and too much of it, is what is needed for liveaboard in the PNW. Diesel heat (or electric when shorepower is available) is really nice. Having too much allows one to open windows. On a boat, the living space is way smaller than a house. Showers, washing dishes, even just breathing can raise humidity onboard.

The little diesel heaters (usually rated at 5 or 8kw) are quite effective, but can be difficult to install in a manner that takes full advantage. Routing ducts to heat 2,3, or 4 areas with a single heater cuts down on efficiency, especially if routed through unconditioned space. One way to get by is to heat one area and use 12V computer fans to move the heated air to other areas. When I intstalled new LED lights, they each had a USB port on them. Little USB fans are also a way to move air around. Can be more efficient and effective than using the ducting that ships with the heater.

I will look into the usb fans, have a 110 fan I use at the dock, but anchored out it’s gonna draw to much power.

 

[SteveK]

Have you looked at running a duct to salon from existing unit?

 

[GrandWood]

Have you looked at running a duct to salon from existing unit?

I have a 90mm going from the rear head to the rear berth, tees and goes up to saloon area, tees on a 60mm into saloon and then the 90 up to the vberth.

 

[SteveK]

OK, you have three outlets, then find a way to close off the aft and V berth ones to push more to salon until you get the balance that works. I am guessing block 50% of those outlets will keep sleeping areas cooler.

 

[luna]

How much heat can you actually expect from a 60mm (round & corrugated?) duct where it is second or third in line, with a 90 mm duct downstream of it?

If your Webasto heater is sized and operating right you will likely be better if upsizing the hot air ductwork and insulating it. I would use smooth walled ductwork.

 

[GrandWood]

How much heat can you actually expect from a 60mm (round & corrugated?) duct where it is second or third in line, with a 90 mm duct downstream of it?

If your Webasto heater is sized and operating right you will likely be better if upsizing the hot air ductwork and insulating it. I would use smooth walled ductwork.

Again nub here, I just installed and am now seeing how it worked out. It’s all a learning experience for me, and have been enjoying it very much.

 

[GrandWood]

OK, you have three outlets, then find a way to close off the aft and V berth ones to push more to salon until you get the balance that works. I am guessing block 50% of those outlets will keep sleeping areas cooler.

I was thinking during the install, as we leave our cabin doors open at night, that hot air rises and would work its way to the saloon, so I didn’t think that I would need more then a 60mm.
Rainy or clouded over days it’s ok, just a hoodie or somethin and alls good, as you know from your GB, once the sun pops out, ya have to open windows even in winter.

 

[Frosty]

How much heat can you actually expect from a 60mm (round & corrugated?) duct .... I would use smooth walled ductwork.

Hi luna,

I'm wondering what type of duct you are suggesting that can be used for high temp and is smooth? Maybe that would give me some more options for a new duct I want to add (I want mine to be smaller than 60mm, but at any rate interested in what general type of smooth duct would be suitable for high temp. I'm not an HVAC expert, but I do understand that ribbed ducting isn't ideal.

 

[Marco Flamingo]

There are no 8 kW Chinese heaters. Two and five. The 8's are a relabeled 5. Yeah $100 a throw -

Must be the tariffs.

I've seen that the 8kW heaters use a different dosing pump than the 5kW units. About 25% larger per tick. Might also have a larger fan. Odd that they can increase the amount of diesel burnt and still be 5kW. What did you find when you dissected them and measured the BTU output?

Every couple of days I burn my webasto full blast to blow out the build up, and for sure you can see the black soot on the dock.

That is one of the reasons why I replaced my Webasto with a higher quality Chinese heater. My CE certified $79 Chinese heater automatically turns on the glow plug and runs the fan on high during a shutdown. Eliminates soot buildup. It never puts soot out on the dock even when I run it inside my boathouse with no wind. My Eberspacher D2 ($1,600) needs occasional cleaning because it doesn't have this feature. The thermostat is also primitive in comparison. My Webasto never ran properly (even the PO admitted) probably because of the no longer available circuit board. I've heard lately that the Germans have copied the Chinese and now use the glow plug on shutdown. Probably cuts down on the lifespan of the glow plug, but a Chinese spare is $40 (which I carry onboard) and the identical Webasto was hard to find, $140, and didn't fix the running problems. Don't throw good money after bad. Go with the safest technology.

 

[Delta Riverat]

I didn't do anything except read utube info stuff. The 2 kW is a smaller size. The 5 is a larger size. As one would expect. The 8 is the same size as the 5. Go figure.

The CE mark on Chinese products is a spoof on the Euro mark, it means nothing as one would expect.

 

[Jeff F]

The CE mark on Chinese products is a spoof on the Euro mark, it means nothing as one would expect.

For sure. I'd say you have no idea what you're buying until you have it in your hands, and even then you're going to have to figure out what makes it tick (!) in the absence of manufacturer support. I'm sure someone will provide a link if I'm wrong.

I'm not arguing against buying one. I had to concede to my son that he'd made a smart purchase. But I wouldn't try to hold them to any formal quality standards or set any specific expectations on performance, or talk about detailed characteristics. We have no idea how many variations on the originals are currently in circulation, or how to identify them. I'm pretty sure Vevor is a brand rather than a manufacturer. They could have multiple sources, all trying to build a better/cheaper product without following any standards.