Air source heat pump

[cornishfarmer]

interesting topic, contemplating ashp or new oil boiler. old farm house, new underfloor heating and rads

 

[br jones]

Not available yet as still being trialled...

There is an ASHP coming that will produce outputs of 65C, on a par with more conventional boilers. This will allow an easier transition from oil/gas boilers for some.

Also hydrogen boilers are being tested

 

[f0ster]

how do you know it can produce 65deg with a decent cop ratio and not just using an immersion heater for the last 10 deg as is the case with lots of these heat pumps, some of them have an immersion heater tucked away inside not easily found unless you know where to look.

 

[borderterribles]

This thread (and the sh*te weather ) has poked me into looking at the running costs of our ASHP, so far. It looks to be on course to be comparable, or slightly cheaper than our last year's oil usage. I would point out that our system is at 7kw, is pretty modest, but the bungalow is lovely and warm. I would also point out that the last heating oil that we bought was dearer than it has been, in the last twelve months.

 

[steveR]

how do you know it can produce 65deg with a decent cop ratio and not just using an immersion heater for the last 10 deg as is the case with lots of these heat pumps, some of them have an immersion heater tucked away inside not easily found unless you know where to look.

The company making them is not one of the type you describe...

 

[Frankzy]

Not available yet as still being trialled...

There is an ASHP coming that will produce outputs of 65C, on a par with more conventional boilers. This will allow an easier transition from oil/gas boilers for some.

There's already plenty ASHP that will produce 60-65 degrees but the problem is that you can't do it without very large inefficiencies.
For example a pump that would normally manage a return of 3,5:1 at -10 will only manage slightly better than 2:1 when producing 60 degree water..

 

[Courier]

how do you know it can produce 65deg with a decent cop ratio and not just using an immersion heater for the last 10 deg as is the case with lots of these heat pumps, some of them have an immersion heater tucked away inside not easily found unless you know where to look.

They need the immersion heater to perform a fortnightly pasteurising process to prevent build up of Legionella bacteria. The regular hot water temperature is not scalding but is certainly too hot to use in a bath without having added cold water.

 

[Chickcatcher]

Just for a bit of Knowledge for others.
Got ASHP in a 1911 total refurbished farm cottage typical school boy drawing was 4 beds now 2 bed en-suite with a bathroom and dressing room all internally insulated new UFH insulated. Single story extension approx. 70SqMtrs 2 OAP residence not happy when cold. I have a down stair Loo that I should have not listened to architect as small it has to much out side wall that should have had extra insulation and needs more heat time than any other room. Stats set at about 21C down stairs.
I like all am concerned that the heat pump is working more than I think it should so started monitoring it again. (was recording on laptop and lost all the info when it got drowned).
January 2021 I have used 3Kw per Hr averaged over the whole 31 day month (746hrs to 1830 tonight) I just wish I had the knowledge of heating costs before I did the house up.
Electric is costing 17p/Kw but when I go over 1000Kw/mnth average I get hit with 20% Vat, Any ideas how I can get this charged at only household rate 5%

 

[Exfarmer]

Just for a bit of Knowledge for others.
Got ASHP in a 1911 total refurbished farm cottage typical school boy drawing was 4 beds now 2 bed en-suite with a bathroom and dressing room all internally insulated new UFH insulated. Single story extension approx. 70SqMtrs 2 OAP residence not happy when cold. I have a down stair Loo that I should have not listened to architect as small it has to much out side wall that should have had extra insulation and needs more heat time than any other room. Stats set at about 21C down stairs.
I like all am concerned that the heat pump is working more than I think it should so started monitoring it again. (was recording on laptop and lost all the info when it got drowned).
January 2021 I have used 3Kw per Hr averaged over the whole 31 day month (746hrs to 1830 tonight) I just wish I had the knowledge of heating costs before I did the house up.
Electric is costing 17p/Kw but when I go over 1000Kw/mnth average I get hit with 20% Vat, Any ideas how I can get this charged at only household rate 5%

I think you can do a declaration that this is a domestic supply. Dicovered I had been charged 20% by mistake for a couple of years and got a refund when I did the declaration

 

[goodevans]

If your close to a livestock building put the ashp up in the gable end ,the air temperature will always be warm enough for high efficiency I would of thought

 

[Courier]

If your close to a livestock building put the ashp up in the gable end ,the air temperature will always be warm enough for high efficiency I would of thought

On a similar vein don’t site an ASHP on the northern side of a building in permanent shadow.

Also northern facing rooms with underfloor piping work better with up to 50 % more length of piping than southern facing rooms with solar gain.

 

[Chickcatcher]

Thanks @Exfarmer will give that a go, @goodevans nowhere near any livestock but a heck of a good idea for a possible future project.
We have Heat recovery units on poultry houses and even exhaust air coming out of these last week were at 11C. We were recovering at least 15C from 18000CuMtrs/hr air flow to put back in as fresh air ventilation lifting -1C to 16C.

 

[xmilkr]

Hi I put a ground source system in five years ago, some under floor some radiators, large 2 bed bungalow, over fifty years old, cavity walls no insulation, so had insulation pumped in FREE under a free heat scheme, cost of g/s system £7500.00 RHI. payments will cover cost, one of the best decisions l ever made.

 

[Chickcatcher]

Dose anyone have a calculation of what lineage of pipe is required per 10Sq/Mtrs of floor space to do its job @chickens and wheat has indicated his water temp is 44c (elsewhere) I suppose heat loss from building structure has a big influence. @xmilkr is your pipe work over flat area or down a bore hole as I have heard some do. I still wonder how Scandinavian countries manage with ASHP when mine just seems to freeze up and thaw more than twice an hour, I sometimes wonder if I gain any heat before it uses the heat to defrost the coil!

 

[Exfarmer]

Dose anyone have a calculation of what lineage of pipe is required per 10Sq/Mtrs of floor space to do its job @chickens and wheat has indicated his water temp is 44c (elsewhere) I suppose heat loss from building structure has a big influence. @xmilkr is your pipe work over flat area or down a bore hole as I have heard some do. I still wonder how Scandinavian countries manage with ASHP when mine just seems to freeze up and thaw more than twice an hour, I sometimes wonder if I gain any heat before it uses the heat to defrost the coil!

ASHP coils freeze in direct proportion to the humidity of the air. There is always going to bbe a problem in the UK‘s maritime climate. As the air drops below zero however the humidity rapidly drops, or the air already frozen air does not attach itself to the coils.
so we have the odd perspective that actually the ASHP efficiency increases dramatically as the air temperature drops below zero.
Their is some very interesting physics with ASHP’s. Obviously the units work best in a warm climate often achieving heat recovery rates up to 8 times the energy input. This will drop as the air temperature drops reaching probably nearer 4-5 to one. However when water is freezing on the fins, heat recovery jumps dramatically due to the heat released as water turns to ice. This of course is lost immediately when the unit goes into reverse mode.
To counter this problem of icing on the fins encountered across virtually the whole of the British Isles , most domestic units incorporate an immersion heater, negating the whole point of the pump just as the unit is needed most, and giving rise to complaints of very high running costs.

 

[chickens and wheat]

Gshp can run hotter but the trade off is efficiency,. 44c is right for me.pump is actually set on 42. With a max on return line of 47.
My pumps can deliver very hot water from the hot gas take off ,I don't use these pipes are capped off, not efficient at all apparently

 

[Puff]

interesting topic, contemplating ashp or new oil boiler. old farm house, new underfloor heating and rads

I would be very wary of sticking in an oil fired boiler what with people's desire to reduce carbon emissions - good chance you would have to replace it. I think hydrogen or electric (ASHP/GSHP etc) will be the near future choices

 

[Courier]

I feel sure that within 10 years, possibly 5 we will see false walls with extra insulation being used on older properties - Slightly smaller rooms in big old draughty farmhouses wouldn't be the end of the world but then damp in the exterior walls could become a problem. Few folk would want to cover up Cotswold Stone exteriors with insulation and render even if planners approved.

 

[Exfarmer]

I would be very wary of sticking in an oil fired boiler what with people's desire to reduce carbon emissions - good chance you would have to replace it. I think hydrogen or electric (ASHP/GSHP etc) will be the near future choices

I am not sure how much oil is costing today, but with gas at 2.5p per Kwh equivalent and electricity pushing up to 18p I think I would take my chance

 

[Home Farm]

We’ve switched to HVO biofuel from kerosene to run alongside our air source heat pump for our winter heating: https://myhomefarm.co.uk/ho-ho-ho-for-hvo-will-it-be-a-warm-christmas

So we’re using the HVO when it cold and the heat pump is least efficient. So far it’s been a good solution.