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Heat pump DIY - heat pump dryer


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Something has been going around head for a few years, but never done anything about it.

 

Heat pump dryers get cheaper and are available second hand. Has anyone tried to utilise the heat pump as a heating system, could you? 

 

System is pretty much like any heat pump. 

 

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16 minutes ago, JohnMo said:

could you

Yes.

But like governing Italy, is it worth it.

 

I suggested something similar from old fridges years back (actually made on to warm the fishpond when I lived in Herts).

Our old mate @Jeremy Harris pointed out that it would be very low powered as fridges usually only draw a few watts, around 100, when running.  So at best, maybe only a 400W output, at 50°C (they don't get much hotter than that as small children may burn fingers).

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Are you planning on dismantling one or just adding the heat output to warm your house? I've used one for 4 years. It does keep the Utility room nice and warm while running but you have to leave the door open as the humidity it puts out is too much for a small room to handle and like any heat pump you need a larger volume of air to draw from. Unless you are super passive it's only going to have a short term localized effect though. It does run in cycles of 2-3 hours so time it right and it could help, you just have to balance the noise with leaving the space open to the rest of the house. It can certainly help but not as much as a dedicated heating system. 

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5 minutes ago, mike2016 said:

It does keep the Utility room nice and warm while running but you have to leave the door open as the humidity it puts out is too much for a small room to handle and like any heat pump you need a larger volume of air to draw from

Could be incorporated into the MVHR to warm the incoming, low RH air.

(you can get MVHR with small built in HPs)

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We use a condensing TD that removes the water from the room.

 

As above such a small heat pump would not give much heat, and if you are not splitting the FGAS circuit, you would have to contrive a way to get one part inside and the other part outside.  Like mounting it through a door or window.

 

It might be a project to keep say a garage a bit warm without costing a fortune, if you can contrive an inside / outside mounting arrangement. But an old fridge would be much easier for that than a condensing TD.

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1 hour ago, mike2016 said:

Are you planning on dismantling one or just adding the heat output to warm your house

So really just a thought process - so just getting a the compressor and the two heat exchangers.

 

But initial thoughts 

 

Do not dismantle the refrigerator circuit.

 

One HE in one bucket of liquid and the other in another. Both buckets connected to 2x 1000L water tanks. One would be heated the other cooled. The heated one would be insulated, the cold one not. Cold one may need an external cooler (car radiator and fan). Then run when above 3 degs only (no defrost needed).

 

Hot IBC would have a long 25mm coil inserted for heat transfer.

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37 minutes ago, JohnMo said:

One HE in one bucket of liquid and the other in another

You could easily make an A2A one from a fridge.

Just constantly pump some air into it (two holes in door, some pipe and a fan) and blow some air over the coils at the back.

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I've occasionally wondered if the price on these was low enough, could you use a bunch of distributed heat pumps to build a general purpose thermodynamic energy transportation circuit around a home. Like a central heating loop of everything. In essence, anything with excess heat output (projector, computers, AV rack, over heating rooms, fridge/freezer, perhaps other kitchen appliances) could pump excess heat into the common water circuit, and anything requiring heat (DHW users, space heating) extract heat out of it. Then an external ASHP just dumps heat into or out of that as required to balance the equation (direction fairly well defined by season).

I imagine herding entropy in this way is an uphill battle against efficiency losses, and the total system complexity and maintenance makes it a non starter, but it's a interesting thought experiment.

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2 minutes ago, joth said:

computers

My laptop is running a bit slow, maybe I can warm it up with my mug of tea.

 

The heat is in the thermal envelope, so no needs.  Energy can be extracted out via the ventilation.

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5 minutes ago, SteamyTea said:

heat is in the thermal envelope, so no needs.  Energy can be extracted out via the ventilation.

One side of the heat pump system in the ventilation duct (extracting waste heat after the heat exchanger in MVHR) and the other heating a buffer or similar?

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1 minute ago, JohnMo said:

One side of the heat pump system in the ventilation duct (extracting waste heat after the heat exchanger in MVHR) and the other heating a buffer or similar?

Not thought of the mechanics of it much.

Still trying to find who it was that made their own.

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15 minutes ago, SteamyTea said:

Still trying to find who it was that made their own.

I recall the one you mean, I believe he used Propane as the refrigerant gas?

 

Was it not a ground source heat pump?  A DIY air source would have to achieve some sort of defrost mechanism which would not usually be required for ground source.

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Just now, ProDave said:

I recall the one you mean, I believe he used Propane as the refrigerant gas?

 

Was it not a ground source heat pump

Yes, propane, can't remember if GSHP or no.

Think it was a lockdown propject

The site search facility really is worse that useless.

Got google search the blogs at the moment.

 

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