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TOPIC: Heat pumps for barge heating

Heat pumps for barge heating 29 Oct 2019 13:11 #111012

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UPDATE

We have now experienced some below zero temperatures and I am pleased to say that the heat pump coped admirably. So it's a success in that it's an effective low-cost heating system.

However, when having to work hard it's a bit noisier than it was when the weather was warmer. It's still quite a lot less noisy than a conventional electric fan heater, but it's not silent. Fortunately the noise is purely wind noise; the mechanical parts are silent, and the noise is low enough not to interfere with conversation or listening to music.

As I mentioned on the Alexa thread, I am now looking into ways to reduce condensation, which is never a problem with a solid or liquid fuelled stove, but is when you are not burning something.
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Heat pumps for barge heating 20 Oct 2019 13:48 #110671

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Charlie,

The advantage of air source is much lower cost, and it's more more convenient to install. Also, I don't have the head-room in the saloon to fit under-floor heating.

However, I agree that your system is superior in every other way.

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Heat pumps for barge heating 20 Oct 2019 09:42 #110653

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Heat pump on viod:
Does all heating and hot water
Primary circuit circulates coolant through heat exchanger welded to outside of hull. Ext water temp usually 3 or 4 degrees on Thames but go works down to 0*. Once it’s been thru heat pump coolant temp - 3 *or -4*.small circ pump keeps it circulating thru heat exchanger (see attached).
Buffer tank above heat pump approx 150 litres is heated to 55*. That water then circulated through coils in hw tanks (2) or thru underfloor heating. In the buffer tank is also a coil which supplies heat from diesel boiler in case of need (very rare). heat pump uses 1.5 kw.

I cannot see advantage of air source heat pump over this system. Heat exchanger not expensive to make and fit, heat pump, Kensa shoebox fairly basic sits there humming way to itself.
C
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Heat pumps for barge heating 19 Oct 2019 00:38 #110611

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I want one! :cheer:

Colin Stone wrote: John,

And this is the chest freezer it copes with:

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Heat pumps for barge heating 18 Oct 2019 17:12 #110601

John,

>That heat exchanger is indeed most impressive.

And this is the chest freezer it copes with:

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Colin Stone
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DBA - The Barge Association
DBA - De Binnenvaartvereniging
DBA - L’Association des Péniches de Plaisance

Heat pumps for barge heating 17 Oct 2019 17:38 #110573

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Peter,

It's quite a simple equation. Provided the water is significantly warmer than the room there will be a transfer of heat. The hotter the water, the smaller the radiators can be. Heat pumps work perfectly well provided the right radiators are selected. And provided the heat pump is properly sized for the building, of course.

My brother has had a heat pump in his house in America for nearly forty years. It works fine, even in very cold weather. But it was installed by people who knew what they were doing.

Peter Cawson wrote: > Moral of the story: heat pump salesmen shouldn't try to replace a boiler with a heat pump unless the existing radiators are also replaced with bigger ones. This might well be impracticable, unsightly, or outside the budget. Or, most likely, all three.

I don't think bigger radiators filled with warm water is any better. Rads require HOT water as it's the difference in temperature between the rad water and ambient that heats your room. In any event, unless the heat pump can provide the required number of kW, your house just won't warm up whatever the size or number of rads. Also, of course, the colder the day, the leas heat you'll get from the pump, at a time when you need most heat! The answer is, as I described earlier, a heat pump supported by a small capacity gas or oil boiler.

Peter

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Heat pumps for barge heating 17 Oct 2019 17:26 #110569

> Moral of the story: heat pump salesmen shouldn't try to replace a boiler with a heat pump unless the existing radiators are also replaced with bigger ones. This might well be impracticable, unsightly, or outside the budget. Or, most likely, all three.

I don't think bigger radiators filled with warm water is any better. Rads require HOT water as it's the difference in temperature between the rad water and ambient that heats your room. In any event, unless the heat pump can provide the required number of kW, your house just won't warm up whatever the size or number of rads. Also, of course, the colder the day, the leas heat you'll get from the pump, at a time when you need most heat! The answer is, as I described earlier, a heat pump supported by a small capacity gas or oil boiler.

Peter

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Heat pumps for barge heating 17 Oct 2019 17:12 #110567

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This is the scenario I described earlier. The irony is that the heat pump may well be producing enough heat; it simply can't dissipate it fast enough through radiators that were designed to operate at a higher temperature.

Moral of the story: heat pump salesmen shouldn't try to replace a boiler with a heat pump unless the existing radiators are also replaced with bigger ones. This might well be impracticable, unsightly, or outside the budget. Or, most likely, all three.



David Warren wrote: I know 2 properties with heat pumps. 1 has a ground source unit which replaced a straw burning boiler on a farm andNeignbours who have 2 air source pumps for a fairly large house. Both of these systems operate radiators and neither can overcome really cold days around 3 degrees or below without additional heat source. I have just had to replace my oil boiler and looked into air source heat pump to heat my hot water and radiators. The cost was excessive compared to a new class A boiler and no guarantee that we could maintain 21 degrees in the house.
They work well with underfloor heating which can run continuously but this is not an option in most existing property.

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Heat pumps for barge heating 17 Oct 2019 14:36 #110559

I know 2 properties with heat pumps. 1 has a ground source unit which replaced a straw burning boiler on a farm andNeignbours who have 2 air source pumps for a fairly large house. Both of these systems operate radiators and neither can overcome really cold days around 3 degrees or below without additional heat source. I have just had to replace my oil boiler and looked into air source heat pump to heat my hot water and radiators. The cost was excessive compared to a new class A boiler and no guarantee that we could maintain 21 degrees in the house.
They work well with underfloor heating which can run continuously but this is not an option in most existing property.

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Heat pumps for barge heating 17 Oct 2019 14:11 #110558

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I can't fault the logic, but it does mean you have had to pay for two heat sources - pump and boiler.

However, I suppose it could make sense as a relatively inexpensive addition to an existing system that would lower the use (and cost) of fossil fuels.

Peter Cawson wrote: > Concerning houses, you do sometimes read of very disappointed customers who installed a heat pump connected to radiators. Because the output from a heat pump is much less hot than that from a boiler the system won't work very well.
> The solution is either to install much bigger radiators (at vast expense) or to use underfloor heating (ditto).

The better solution surely is to send the heat pump water(hot or warm) through a low capacity conventional boiler. If its thermostat sees hot water coming in, it won't fire up - it the water is only warm, it will fire up, but it will require far less energy to bring the water temperature to what the radiators need.

Peter

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Heat pumps for barge heating 17 Oct 2019 13:53 #110557

> Concerning houses, you do sometimes read of very disappointed customers who installed a heat pump connected to radiators. Because the output from a heat pump is much less hot than that from a boiler the system won't work very well.
> The solution is either to install much bigger radiators (at vast expense) or to use underfloor heating (ditto).

The better solution surely is to send the heat pump water(hot or warm) through a low capacity conventional boiler. If its thermostat sees hot water coming in, it won't fire up - it the water is only warm, it will fire up, but it will require far less energy to bring the water temperature to what the radiators need.

Peter

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Heat pumps for barge heating 17 Oct 2019 13:30 #110556

John,

And being watercooled, the COP is excellent so a 90 ltr under floor chest freezer is very economical.

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Colin Stone
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DBA - The Barge Association
DBA - De Binnenvaartvereniging
DBA - L’Association des Péniches de Plaisance

Heat pumps for barge heating 17 Oct 2019 13:17 #110555

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Colin,

That heat exchanger is indeed most impressive.

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Heat pumps for barge heating 17 Oct 2019 13:15 #110554

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Concerning houses, you do sometimes read of very disappointed customers who installed a heat pump connected to radiators. Because the output from a heat pump is much less hot than that from a boiler the system won't work very well.

The solution is either to install much bigger radiators (at vast expense) or to use underfloor heating (ditto).

There is also a tendency to under-spec the heat pump, which accounts for installers saying they work best in very well-insulated houses! Idiots. I am fully aware that I have probably under-spec'd mine, but that was all part of the plan. If it works as well as I hope I might well install another to heat the stern, when required, and if it doesn't it will at least reduce my dependence on fossil fuel to some degree. It will be very nice to have air conditioning in summer, too.

And if it works better than hoped, a second unit may be unnecessary.

Paul Hayes wrote: Hi Charles / John

Charles you are correct a water source heat pump is more efficient. But something like four or five times the capital outlay (even if doing a lot of work DIY).

John, no pipes around the hull, water is drawn in through a sea cock, passed around the condenser coils, in a watertight outer casing) and discharged back overboad.

Traditionally the C.O.P. Coefficient of Performance) i.e. the amount of usable energy (heat) extracted from the air for every unit (kW) of electricity was around 3:1. Although clever design has improved on this. Ground or Water source have been in the region of 3.75 - 4:1. Again there's a constant desire for improvement. But either is preferable to heating with resistance based electrical heating.

There is a big push at the moment to install air and ground source units to houses, with the government almost giving it away in some cases by offering large subsidies.

Water source will probably have greater long term maintenance requirements, as the water delivery system is more complex than a coil and a fan.

Paul Hayes

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Heat pumps for barge heating 17 Oct 2019 10:39 #110552

I have seen a skin fitting in USA which is a twin wall skin fitting with the refrigerant in the middle. It is intended as the inlet for the generator which powers the heat pump. The flow of water keeps the refrigerant cool.
Not so good in the marina but good when away or underway.

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Heat pumps for barge heating 17 Oct 2019 09:32 #110550

Perhaps someone will develop a keel cooler for water heat source systems. I have this keel cooler for my deep freeze. So the water condenser coil is tiny compared to the air cooled grid unit to do the same job.

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DBA - De Binnenvaartvereniging
DBA - L’Association des Péniches de Plaisance

Heat pumps for barge heating 17 Oct 2019 09:11 #110548

Hi Charles / John

Charles you are correct a water source heat pump is more efficient. But something like four or five times the capital outlay (even if doing a lot of work DIY).

John, no pipes around the hull, water is drawn in through a sea cock, passed around the condenser coils, in a watertight outer casing) and discharged back overboad.

Traditionally the C.O.P. Coefficient of Performance) i.e. the amount of usable energy (heat) extracted from the air for every unit (kW) of electricity was around 3:1. Although clever design has improved on this. Ground or Water source have been in the region of 3.75 - 4:1. Again there's a constant desire for improvement. But either is preferable to heating with resistance based electrical heating.

There is a big push at the moment to install air and ground source units to houses, with the government almost giving it away in some cases by offering large subsidies.

Water source will probably have greater long term maintenance requirements, as the water delivery system is more complex than a coil and a fan.

Paul Hayes

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Heat pumps for barge heating 17 Oct 2019 01:10 #110545

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Charlie,

Whilst I agree that a water source heat pump is a wonderful thing, and perfect for a static houseboat, it is not such a practical idea for a boat that moves. BTW, what you have on Vlod is a water-source heat pump, not a ground-source heat pump (which involves piped buried in the ground).

It is possible of course that you have devised a system of pipes running through or around the hull which will continue to work while underway (assuming you are generating sufficient electricity to run it). They might well, however, slow you down, and they will certainly have cost rather more than £1,300.

And whilst a water-source heat pump is slightly more efficient than an air source heat pump, that doesn't mean the latter are inefficient. A great many commercial properties in the UK (and abroad) use air source heat pumps. As do many residential properties in continental Europe.

At the end of the day, however, I am advocating a heat pump (water or air-source) for boats that are static in winter, and which have access to at least 16A electricity. If these two factors don't hold true, then it's not going to work very well.

Cheers

Charles Mclaren wrote: I am slightly confused here. I have a heat pump on Viod but it extracts its heat from the water, a ground source heat pump. As I understand it that is a far more efficient system than an air source heat pump. We all live on the water where the temperature Of the warr by definition never goes below 0°C. I do have shorebased electricity, without which I cannot see any heat pump is a realistic possibility for a barge. I have a diesel boiler for use when under way. My question, if you are on the mains electricity why would you have an air source heat pump when you could have a ground source heat pump. What am I missing here? Viod is 32 m and has underfloor heating throughout and 2 calorifiers. Charlie

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Heat pumps for barge heating 17 Oct 2019 00:23 #110543

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I am slightly confused here. I have a heat pump on Viod but it extracts its heat from the water, a ground source heat pump. As I understand it that is a far more efficient system than an air source heat pump. We all live on the water where the temperature Of the warr by definition never goes below 0°C. I do have shorebased electricity, without which I cannot see any heat pump is a realistic possibility for a barge. I have a diesel boiler for use when under way. My question, if you are on the mains electricity why would you have an air source heat pump when you could have a ground source heat pump. What am I missing here? Viod is 32 m and has underfloor heating throughout and 2 calorifiers. Charlie

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Heat pumps for barge heating 16 Oct 2019 23:53 #110542

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Peter,

I agree that if your mains supply only offers a very low amperage then this won't work. In the UK most supplies are 16A, and a few are 32.

Where I am the supply is 16A, and so far I have not experienced a problem, despite having a tumble dryer and a 3kW immersion heater. Those two are in an either/or circuit, so they are never on at the same time, but one or other has been on at the same time as the heat pump. Unless the weather is very cold the unit is using very little electricity. In the depths of winter I shall probably have to be careful about what is on when. This might mean, for instance, putting the immersion on a timer so that it only operates at night.

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Heat pumps for barge heating 16 Oct 2019 20:54 #110539

Hi Peter
The situation I refer to is in central France livaboard, the heating season runs from end of October to April, On a 16 amp shore supply many people use some type of electric heating for part of their requirements, oil filled radiators are a favorite.

Power hungry appliances, most use gas for cooking, low wattage kettles, 1 kW immersion heater and balance one "Heavy Load" at a time, as we do, one dishwasher, one washing machine, one tumble dryer, one hair dryer. Its all about knowing your boat and thinking before switching on. Battery chargers on all day pull hardly anything. It's never an inconvenience, just thinking in advance.

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Heat pumps for barge heating 16 Oct 2019 18:17 #110538

> Yes, indeed. It's very much a system for a boat on a mooring with mains electricity.

1385 watts is about 5.8 amps. Many shore supplies are only 6 amps, or 10 maybe, although a few offer 16.

How do you cope with other power-hungry devices when your heat pump is operating? A microwave, hob, oven, kettle, toaster, or even your domestic battery charger will bring your demand well over10 Amps and likely to trip the shore supply.

I can see their advantage in a house, or I suppose a houseboat, where plenty of power is available on tap, but boats have very limited availability. I wouldn't want to have to start a generator anywhere there's a shore supply - and therefore neighbours!

Would you recommend this system for a cruising vessel that may sometimes be stuck with a low to medium current shore supply, or reliant on its own resources when moored in remote locations? I'd dearly like to scrap my horrid hot air Webasto, but I don't like the sound of a heat-pump based system!

Peter

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Heat pumps for barge heating 16 Oct 2019 17:19 #110535

Hi John we quite regularly get well below -10, hopefully alleviate your worries about ice, when it gets that cold for a period of more than 2 o 3 days the relative humidity drops to an extent that all of the water is trapped in frost on the trees, even car windscreens don't need scraping.
There should be an auto defrost on the external condenser ( like you have in a domestic fridge) that will take care o ice buildup.
We have friends who use one and you are correct below about 5C they need another heat source to be really comfortable.

They do run the Genny in the summer for AC off grid.

DIY units, pre gassed are very much cheaper in French Bricos, about 600E buys one the size you mention.

Let us know in a years time as I'm sure others would like to hear how you get on

Paul Hayes

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Heat pumps for barge heating 16 Oct 2019 16:55 #110534

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The way these things work is by lowering the temperature of the air that is forced through them, and the heat thereby released is captured by the refrigerant and transmitted into the living space . Whatever the air temperature, you can always make it lower. In theory anyway.

In practice, ice formation would cause the unit to stop in order to clear the ice, and this would render it less effective. There are probably other factors that play a part.

My unit is guaranteed to work down to minus 15, but it does admit that it will work less well at that temperature. It should, however, be OK at zero, and other boat owners I know who have heat pumps say they work fine when it's zero degrees.

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Heat pumps for barge heating 16 Oct 2019 16:29 #110533

I have one 10 years old heat pump in my house and it is the only heating device even one year when the temperature dropped below -11°C.
Theorically heat pumps are able to suck calories from air as low as -20°C.

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Heat pumps for barge heating 16 Oct 2019 16:22 #110532

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I have had these in the US for home heating and I have three at my home in Malta. Their ability to generate heat drops a lot when the temperature falls below 6 or 7 degrees C. It never gets that cold in Malta so its a good deal there. But in the US it required additional electric heat for those colder days. There just isnt enough ambient heat in the air for the unit to work. Will be interested to hear how it works this winter.

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Heat pumps for barge heating 16 Oct 2019 14:38 #110527

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Colin,

cypin.com/ru/product/single-splits-rac-wall-mounted-srk45zmp-s-src45zmp-s/

The input is actually 1.385kW, so nearly 1.4.

I think you would struggle to run AC on the panels you mention. On a hot day the efficiency of solar panels is reduced and you might find you wouldn't have quite enough power. It would of course be free power, and if you have room it might be worth installing a couple more panels.

Or get a smaller heat pump.

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Heat pumps for barge heating 16 Oct 2019 14:25 #110525

Sounds good.

In summer it could run off solar for cooling during the hot part of the day. 4 360wp panels should just about suffice.

Would be good to know make/model??

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Heat pumps for barge heating 16 Oct 2019 14:20 #110524

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Yes, indeed. It's very much a system for a boat on a mooring with mains electricity.

But, that is a category that includes a great many boats in winter. In summer, when out and about, heating is much less of an issue.

Peter Cawson wrote: > It produces 5kW of heat or 4.5kW of cooling for an input of 1.3kW of electricity, which means it is very economical

Sounds interesting but where do you get your 1.3 kW from when n o shore supply available? It would be crazy is have to use the generator!

Peter

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Heat pumps for barge heating 16 Oct 2019 14:15 #110523

> It produces 5kW of heat or 4.5kW of cooling for an input of 1.3kW of electricity, which means it is very economical

Sounds interesting but where do you get your 1.3 kW from when n o shore supply available? It would be crazy is have to use the generator!

Peter

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Heat pumps for barge heating 16 Oct 2019 14:10 #110522

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I have recently installed a dual purpose air-to-air heat pump in my boat, and thought other people might be interested in my experience.

It was not expensive (£1,300 fitted) and I am very impressed so far. However, the weather hasn't yet been cold enough to test it properly.

It produces 5kW of heat or 4.5kW of cooling for an input of 1.3kW of electricity, which means it is very economical.

These things are reputed to be highly reliable, so I had no fears on that score. However, I did have two concerns. The first was noise, and the second was whether it really would be effective at temperatures down to zero degrees. Since such temperatures are not common where I am, I reckoned that it would be cheaper to augment the heat pump when necessary with other forms of heating rather than get a significantly bigger unit which would seldom be used at full capacity. I will report back after we've had some low temperatures.

As far as noise is concerned, I need not have worried. The external unit is silent for all practical purposes, and completely free of vibration. The internal unit is also silent most of the time, but I can sometimes hear a gentle noise caused by a rush of air. It's much much quieter than a fan heater, so it really isn't an issue.

There are two surprises. The first is that I am, unexpectedly, suffering very little from condensation. The dehumidifier rarely switches on and produces very little water.

The other surprise is that the programming is rather basic. The machine will switch on and off when required by the timer, but will only maintain one temperature. However, there is a simple solution. I am fitting an always-on thermostat set to a low temperature, and a timer for daytime operation. During the day, the machine maintains the set temperature (I find 19 degrees is OK) and at night, when the timer is off, the machine gets power from the thermostat. Once the temperature exceeds 10 degrees the thermostat switches off the power.

All in all, I am extremely happy with this addition. Furthermore, it's cheap enough for people to install who don't use their boats much in winter, but would like an effective, cheap, and simple form of heating when they do. Being an air heater, it acts very quickly.
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