ASHP for a single 100m UFH loop?

[Radian]

The loop in question forms a 24m2 area so for 75W m2 only requires around 1.8kW  All the 'small' ASHP I can find start at 5kW output and are physically too large as I only have a 1.2m wide corridor to fit the outdoor unit into. Technically I see no reason why a system couldn't be made to the kind of spec's I need. After all, certain EV's use them for heating the cabin. I just can't seem to track one down. Air-to-air compressors are also sized about right for this but aren't going to get me hot water.

[JohnMo]

What about a solar assist heat pump, they are generally around 2kW, come with 2 off 2x1m panels for outside though and they need to be mounted. Or if you like engineering something, could you use a  car Aircon condenser and car fan, instead, mount in a custom box. Use it to heat a 50/100 litre cylinder with coil and take the UFH water from that.

 

Or a Willis heater, CoP 1 though, so may be costly to run.

 

Or an all in one air to air heat pump, for cooling and heating. But that doesn't used the UFH.  But no outside unit.

[SuperPav]

What about something like this, depending on your internal layout and duct routing options? An integrated cylinder with heat pump.

 

https://www.heatershop.co.uk/dimplex-edl200uk?gclid=CjwKCAjwlcaRBhBYEiwAK341jdz8DNVbnJrzxbk1ovEi_RGvJ_EbNp7dLREhL5O8TUwt0wVa5byJAhoCbJ8QAvD_BwE

 

Although I have never used one so don't know how efficient they are.

 

 

 

[Radian]

38 minutes ago, JohnMo said:

What about a solar assist heat pump, they are generally around 2kW, come with 2 off 2x1m panels for outside though and they need to be mounted.

 

Very intriguing, not seen this before! 

Says the panels can be wall mounted. 2kW out for 500W in. Perfect... If only I could find a price someplace.

 

45 minutes ago, JohnMo said:

Or if you like engineering something, could you use a  car Aircon condenser and car fan, instead, mount in a custom box. Use it to heat a 50/100 litre cylinder with coil and take the UFH water from that.

 

My kind of hack alright, but not much can be done without messing around with refrigerant which is a no-no.

 

48 minutes ago, JohnMo said:

Or a Willis heater, CoP 1 though, so may be costly to run.

 

 

Yes, well that was the plan before the prospect of paying  50p/kWh reared its ugly head.

[Radian]

25 minutes ago, SuperPav said:

What about something like this, depending on your internal layout and duct routing options? An integrated cylinder with heat pump.

 

https://www.heatershop.co.uk/dimplex-edl200uk?gclid=CjwKCAjwlcaRBhBYEiwAK341jdz8DNVbnJrzxbk1ovEi_RGvJ_EbNp7dLREhL5O8TUwt0wVa5byJAhoCbJ8QAvD_BwE

 

Although I have never used one so don't know how efficient they are.

 

 

 

Interesting but pricey. So just two 160mm holes in the wall to outside. Doesn't say anything about how far apart they need to be though.

 

From datasheet: 700W in 1650W out = COP 2.35 which is not very promising. Very little info to go on though.

[SteamyTea]

I found (well someone else did) a 3.6 kW (may have been a 3.8) ASHP.

A bit of searching on here should find it.

All I need is a very small ASHP and keep wondering if a very basic swimming pool one, connected to the heating via a decent size buffer, will do the job. Not as if it will run for very long.

 

[PeterW]

3 minutes ago, SteamyTea said:

I found (well someone else did) a 3.6 kW (may have been a 3.8) ASHP.

A bit of searching on here should find it.

All I need is a very small ASHP and keep wondering if a very basic swimming pool one, connected to the heating via a decent size buffer, will do the job. Not as if it will run for very long.

 

A lot of the pool ones don’t have defrost on them so can only be run when it’s over 8°C or they ice up. Mate has one on a koi pond - will check what make his is as it’s not very big !

[SteamyTea]

4 minutes ago, PeterW said:

A lot of the pool ones don’t have defrost on them so can only be run when it’s over 8°C or they ice up. Mate has one on a koi pond - will check what make his is as it’s not very big !

Yes, but as it will only run for a short time, frosting may not be an issue.

When I get home i shall see if I can find the little pump someone suggested. When I looked at the physical size, it was the same as the 5 kW one. And probably more expensive.

[PeterW]

Here you go - £875 for a 3.75kw plug and play unit and works to -10°C according to the spec sheet 

 

https://www.automatedenvironmentalsystems.co.uk/product/remora-mini-swimming-pool-heat-pump-with-wi-fi/?attribute_model=Remora+Mini+m3+Wi-Fi+-+3.98kW+Plug+%26+Play+(230v)&gclid=CjwKCAjwlcaRBhBYEiwAK341jcVRON-oU02GLGFhBE1JP7RZqcu8LD5perhb4ai_7ND_rTyhro59UxoCKy4QAvD_BwE

[SteamyTea]

Here we go, with thanks to @Trw144

https://www.wolseley.co.uk/product/vaillant-arotherm-plus-air-source-heat-pump-35kw/

 

 

[Radian]

The problem I see with pool heaters is they all seem to max out at 29C. Might just be hot enough for UFH but few seem to operate at air temperatures below 10C. But the core components are tantalisingly close to the specs required for a small space heating task. Obviously the £2.5K price gap with the arotherm is utterly artificial.

[SteamyTea]

50 minutes ago, Radian said:

The problem I see with pool heaters is they all seem to max out at 29C

That other ASHP you found, the Chinesium one for £1200.

If I remember it had an output temperature of 60°C, plenty in other words.

If the heat demand (actually power required) is relatively low i.e. less than half the rated output, most of the time.  Fitting a large buffer should allow for relatively short running times and help to keep the CoP high as you can store at say 50°C.

So in effect the modulation is done in the buffer tank, rather than the compressor.

Similar to what microchips do when they 'race to the end', or whatever the spotty oiks call it, to save energy.