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Old 10-16-2020, 05:07 PM   #21
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So, is it safe to conclude that the more raw water one can push through the units, the better cooling/heating? For example, Oberdorfer makes an AC pump that puts out 1,440 GPH. My pump puts out 900 GPH.
It won't give you that much more heating. Decreasing the temp drop from 10 to 5 degrees probably increases the COP from 1.5 to 1.6 (7%) just like an air cooled or heated mini split increases with OAT going up 5 degrees from 35 to 40 degrees.

The more significant benefit is that you can operate at lower OAT and water temps without freezing up in really cold conditions.

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Old 10-16-2020, 05:09 PM   #22
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So, is it safe to conclude that the more raw water one can push through the units, the better cooling/heating? For example, Oberdorfer makes an AC pump that puts out 1,440 GPH. My pump puts out 900 GPH.
For the most part, no. Use the pump size spec'd for your system. You risk cavitation issues, to name one, with an oversized pump that the plumbing and compressor system is not designed for.
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Old 10-16-2020, 08:36 PM   #23
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Yes temp measured in and out. Along with sensors measuring air temperature/ humidity through out the house. Also measure barometric pressure in/out of house. House kept at slight positive pressure and what ever humidity/temperature you want in each zone you want. Also heat exchangers so internal air is cycled but filtered (13)
Temperature of earth once you get that deep is constant. How deep You need to go depends on geology. Nothing else
Sounds like you have a pump and dump system with a heat exchanger. Closed loop systems have differential above ground temperature (absolute heat exchange doesn't happen in closed loop systems).

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Old 10-17-2020, 08:09 AM   #24
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No it’s closed loop. We live on the shore of a pond inside a park. One of 12 grandfathered residential lots. Open loop is illegal by fed, state and municipal rules due to where it is. Watched them dig the holes. They went through sand, clay, ledge and rock. A geological survey was done first. Engineer determined at 200’ ground temperature would generate 55f at exit year round. So we went 50’ further to be safe. Monitoring systems say he was spot on. Closed loop placed inside a pipe and pipe goes down hole. Run to basement inside a trench below ground freeze line and insulated. Inside house heat pumps and air handlers. Separate set up in attic to handle second floor. Interface water/air. To meet air turnover requirements separate heat exchangers for air in and out of house so minimal loss of cooling or heating. Air is filtered coming in to the house but also as it circulates in the house. Electricity supply is solar to grid then grid to units. If grid goes down kohler generator. So net is zero footprint with a monthly check to us even after our other electrical draws. Only maintenance so far has been changing air filers. Have gone with MERV 13 filters so get hospital grade air. No allergies and lower risk of infectious disease. Did gas house when it was completed before occupancy so no mold spores. I have a mold allergy. Biggest problem that was unexpected was due to going to commercial grade hood over stove having to re-engineer system to allow for additional air egress when hood was running. Our ingress and egress 80% of the time is through the garage then mud room. Garage is heated. Bathrooms heated through floors as well as geo. Our HERS rating is better than over 90% of houses in the state so got credit. Spent a fair amount of time with geo HVAC vendor and architect and builder and engineer to get it right. Able to maximize efficiencies, tax credits and hold expenses down. Still, it costs more at every level to do this (windows, foam insulation, thickness of framing etc.) but it’s a one and done expense. Calculations with current energy costs give us a pay off at 4 years due to incentives. After that it’s money in our pockets with a more comfortable house. Strongly suggest anyone building a new house do a zero footprint house with solar and geo. Not only for environmental reasons but it makes economic sense and you get more comfort.
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Old 10-17-2020, 08:43 AM   #25
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As discussed there the efficacy of the heating function decreases with water temperature. When the water is cold, there is little heat to extract. At around 40 the results are about nil.

So there is a plethora of solutions to heat the boat beyond that point, the details of which I do NOT want to get in to here. What they all have in common though, is that on a large(r) boat they will need considerable additional installation of plumbing and/or wiring to distribute to the far corners of the vessel.

We still had very good heat with our systems in 40F water temps.

Some liveaboard boat neighbors added a resistance heat unit to their reverse cycle system -- coincident with replacing all their very old stuff with new -- so the resistance unit could work using the existing ducting when our harbor froze over. Said it worked very well... and since that was an auxiliary, they said it didn't cost them an arm and a leg in electricity for the little mount they needed it.

Though I think they also sometimes used one or two plug-in oil radiator heater thingies sometimes, too... and an electric blanket.

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Old 10-17-2020, 09:44 AM   #26
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Heat pumps are rated by their coefficient of performance which is KW of heat out divided by KW of electricity in. A boat reverse cycle unit which isn't terribly effiecent, has a COP which varies from about 2.5 for water temps of 60F to 1.0 for water temps of about 20F assuming that the water doesn't freeze (I know, it will).

When OATs got down to 20F at my home which had heat pump heat (which also wasn't very efficient), I would turn the thermostat to emergency heat which switched it to resistance heat. Resistance heat has a COP of 1.0.

The point is that reverse cycle heating continues to work effectively in a boat, although at reduced heat output, down to where the water freezes up which might be 35-40F inlet temps because the water is cooled about 5-10F in the evaporator.

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Old 10-17-2020, 10:07 AM   #27
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Been thinking a lot about this. Want to buy on east coast of US or Caribbean but boats here usually don’t have heat whereas Pacific Northwest commonly do. Have put in offers on N40s but so far without success. Since last boat had wesbasto and prior Espar or drip know how much independent heat improves quality of life. Like Canadian maritimes and Washington county Maine. Waking to a warm boat is so nice. Both the N40 and 43 don’t have room for a good drip diesel heater to my eye whereas the 46 does in the saloon. Retrofitting hydronic is big money.
What would be your suggestions for independent heat in a small Nordhavn?
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Old 10-17-2020, 10:18 AM   #28
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Originally Posted by Hippocampus View Post
No its closed loop. We live on the shore of a pond inside a park. One of 12 grandfathered residential lots. Open loop is illegal by fed, state and municipal rules due to where it is. Watched them dig the holes. They went through sand, clay, ledge and rock. A geological survey was done first. Engineer determined at 200 ground temperature would generate 55f at exit year round. So we went 50 further to be safe. Monitoring systems say he was spot on. Closed loop placed inside a pipe and pipe goes down hole. Run to basement inside a trench below ground freeze line and insulated. Inside house heat pumps and air handlers. Separate set up in attic to handle second floor. Interface water/air. To meet air turnover requirements separate heat exchangers for air in and out of house so minimal loss of cooling or heating. Air is filtered coming in to the house but also as it circulates in the house. Electricity supply is solar to grid then grid to units. If grid goes down kohler generator. So net is zero footprint with a monthly check to us even after our other electrical draws. Only maintenance so far has been changing air filers. Have gone with MERV 13 filters so get hospital grade air. No allergies and lower risk of infectious disease. Did gas house when it was completed before occupancy so no mold spores. I have a mold allergy. Biggest problem that was unexpected was due to going to commercial grade hood over stove having to re-engineer system to allow for additional air egress when hood was running. Our ingress and egress 80% of the time is through the garage then mud room. Garage is heated. Bathrooms heated through floors as well as geo. Our HERS rating is better than over 90% of houses in the state so got credit. Spent a fair amount of time with geo HVAC vendor and architect and builder and engineer to get it right. Able to maximize efficiencies, tax credits and hold expenses down. Still, it costs more at every level to do this (windows, foam insulation, thickness of framing etc.) but its a one and done expense. Calculations with current energy costs give us a pay off at 4 years due to incentives. After that its money in our pockets with a more comfortable house. Strongly suggest anyone building a new house do a zero footprint house with solar and geo. Not only for environmental reasons but it makes economic sense and you get more comfort.
My geothermal project was 4 tons with 12 wells 100' deep. Because of a contaminated aquifer, wells couldn't be 200 to 275' deep, no piercing the clay layer at 120'. All in about $26K. After federal, state and power company tax credits, cost was about $12k. Duct work was already in place. Looked at solar and concluded my $100 per month electric bill wasn't worth the investment.

Ted
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Old 10-17-2020, 10:30 AM   #29
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Originally Posted by catalinajack View Post
So, is it safe to conclude that the more raw water one can push through the units, the better cooling/heating? For example, Oberdorfer makes an AC pump that puts out 1,440 GPH. My pump puts out 900 GPH.
If I had known what I know now when I did my refit, each unit would have been plumbed individually with its own 900 GPH pump and 1" hose. The added electrical cost would easily been offset by increased efficiency and shorter run times. Would probably use the same though hull and strainer with isolation valves before the pumps.

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Old 10-18-2020, 07:23 AM   #30
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The drip heaters like the Dickinson work well, there limited to about 20,000 btu and with a gravity fuel system need zero electric , so a winter on the hook becomes reasonable.

I lived aboard for a couple of decades in the NYC area and was a dealer for Dickinson and Espar.

Many folks found that the 16-20,000btu worked fine but a few needed 2 heaters , a range and a second unit for the really cold -0F weeks .

My personal choice was a floor mounted unit with 3/4 finned tubing and only thermosyphon to move the water. As the total head was small , perhaps 7ft I was not sure it would work.

Hooked up for the first winter I used rubber heater hose and was delighted , it worked.

The second summer I replaced the rubber hose with copper tubing and fittings , & the circulation stopped working .A few reference books (Algore had not invented the internet yet) and I learned of the high resistance of 90deg elbows.

The refrigeration folks have "slow" elbows and 45deg fittings so I replaced the plumbing items with fridge stuff. It then worked.

I found that a constant temp of 135F of the circ water was perfect for indoor T shirt comfort. I was the thermostat .

The unit , once fitted with the proper H smoke head was reliable enough to go to work 2 to 4 days , depending on weather.

The extra heat required if a quick start was needed came from a Shipmate wall fireplace,loaded with charcoal it would heat all night.

Other companies make drip pot heaters that are larger.


I had tried the Espar on a previous boat , a 45 ft cold molded Tri and found that due to the light construction and lack of insulation (to avoid condensation in the wood surfaces) the operating noise was hard to live with.

The unit sounded like a Hoover in the next cabin.

On a really big boat I would install baseboard heating tubing and a Peerless or other premium house oil furnace , an inverter and a big pile of batts, for when the dock is down.


https://www.peerlessboilers.com/products/series-wbv/
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Old 10-18-2020, 08:14 AM   #31
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There is plenty of heat in 40F sea water for a rev cycle machine to extract. The problem is if ice starts to form in the heat exchanger. A bit of ice forms and this reduces flow, which allows more ice to form. Then the problem literally "snowballs" til flow is choked off.

This problem is way worse if water flow is low. With four units on one pump the OP probably has a lot of plumbing, and some units might get plenty of flow, some might be on the low side.

Also some units are better at cold operation than others.

Just an idea that popped in my head (not super well thought through) is to have two pumps in parallel, with the second pump left off unless in cold temps, then switch to both on to increase flow. Just thinking aloud.
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Old 10-18-2020, 09:47 AM   #32
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FF did you need fans to move the air around? What kind of boat where you living on?
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Old 10-18-2020, 10:06 AM   #33
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Anyone here have experience with Reflecks diesel heaters?
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Old 10-18-2020, 10:07 AM   #34
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Originally Posted by catalinajack View Post
So, is it safe to conclude that the more raw water one can push through the units, the better cooling/heating? For example, Oberdorfer makes an AC pump that puts out 1,440 GPH. My pump puts out 900 GPH.
Oscar, increasing flow as CJ posts only works to a point.

Increasing water flow with a larger pump assumes your suction and discharge piping is upsized as well to keep friction losses in check. The same holds true for the heat pump unit itself. They are sized for flow too.

Have you considered a passive diesel fired unit like Dickenson? Relatively inexpensive and lots of them out there.
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Old 10-18-2020, 01:36 PM   #35
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How,does the Dickerson compare with other brands. Specifically Reflecks. See more Reflecks on voyaging sailboats and high lat craft. why?
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Old 10-18-2020, 03:42 PM   #36
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How,does the Dickerson compare with other brands. Specifically Reflecks. See more Reflecks on voyaging sailboats and high lat craft. why?

Sure, either would work. So would a few well placed electric heaters. There are several cost effective many options for heating a vessel for those periods when water temps are marginal for reverse cycle.

We have four heat sources. Diesel hydronic, engine heat, reverse cycle and electric spot heaters.
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Old 10-19-2020, 06:45 AM   #37
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"FF did you need fans to move the air around? What kind of boat where you living on?"

Fans were not needed the heating unit was in the main aft cabin, galley and dining with Concordia bunks .


The hull and deck is Airex , s slight insulation.


A single 4 ft section of heat tubing warmed the the pilot house ,return was in engine space and the fwd cabin had a 6ft and and an 8 ft section of finned tubing ft .
The fwd return tube was thru the hanging locker so there was no problem with uniforms etc.

There are fans that work on a hot surface , I have seen them used with 40ft sail boats to move the heat in a cabin.
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Old 10-19-2020, 07:00 AM   #38
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Has anyone thought about using a hot water heater on board to heat hydronic baseboard or the like? Obviously need 120 volts. I have a friend who heated a 3,000 sq foot barn with a domestic hot water heater and a radiant floor
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Old 10-19-2020, 07:20 AM   #39
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Has anyone thought about using a hot water heater on board to heat hydronic baseboard or the like? Obviously need 120 volts. I have a friend who heated a 3,000 sq foot barn with a domestic hot water heater and a radiant floor

Given a big enough water heater, it'll work. But it's no better in terms of power in vs heat out than just using space heaters.
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Old 10-19-2020, 07:31 AM   #40
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Great responses . Thanks all.
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