ASHP with solid walls

Kiittykatz

I have bought a property that has solid walls and wish to install ASHP heating as the property currently only has electric heating. I have now uncovered all the insulation that is recommended for ASHP to work efficiently and control my electric costs. Has anyone here had experience of ASHP with solid walls that they have not insulated externally or internally. I do not wish to render the house as it is expensive and changes the appearance of the house, and the internal insulation means I lose floor space - not ideal. Interested in peoples experiences - thanks 

Screwdriva

Can I ask if the property has electric radiators or electric underfloor heating? 

If so, these will need to be replaced by a wet system if getting an air to water heat pump, which can get pretty expensive.

I suspect it may make more fiscal sense to get a Air to Air heat pump solution for this property and a separate hot water cylinder with built in heat pump like the new Mixergy iHP. Air to Air systems typically have a more consistently high SCOP but you will need to insulate the property to really see a benefit from this. You'll still need electric towel rails and/or UFH for the bathrooms though. 

Internal insulation (55mm insulated plasterboards) is effective and you will need double glazing and 300mm of loft insulation as well. 

shinytop

Kiittykatz said:

I have bought a property that has solid walls and wish to install ASHP heating as the property currently only has electric heating. I have now uncovered all the insulation that is recommended for ASHP to work efficiently and control my electric costs. Has anyone here had experience of ASHP with solid walls that they have not insulated externally or internally. I do not wish to render the house as it is expensive and changes the appearance of the house, and the internal insulation means I lose floor space - not ideal. Interested in peoples experiences - thanks 

No direct experience but I went from storage heaters to ASHP and am very pleased. I assume you have done the easy stuff like loft insulation?  If you have, and have a relatively draught free house there is no reason why a well designed A2W ASHP won't won't work with solid walls.  You'd need appropriately sized radiators so they can work at low-ish temperatures. As @screwdriva says, it won't be cheap. Mine was £16k or so, fortunately for me mostly paid for by RHI.  

It's all about the heat loss of your house.  If youn work that out you'll get a good idea of how an ASHP might work. You could have a go at doing the calculations yourself or get a quote from a supplier, although you'd probably have to pay for that. There are a few calculators available online, shout if you want some links. 

Remember that an ASHP system will use about 1/3 of the energy your current direct electric system does.  

Kiittykatz

Screwdriva said:

Can I ask if the property has electric radiators or electric underfloor heating? 

If so, these will need to be replaced by a wet system if getting an air to water heat pump, which can get pretty expensive.

I suspect it may make more fiscal sense to get a Air to Air heat pump solution for this property and a separate hot water cylinder with built in heat pump like the new Mixergy iHP. Air to Air systems typically have a more consistently high SCOP but you will need to insulate the property to really see a benefit from this. You'll still need electric towel rails and/or UFH for the bathrooms though. 

Internal insulation (55mm insulated plasterboards) is effective and you will need double glazing and 300mm of loft insulation as well. 

Hey Screwdriva, It is electric radiators that will be ripped out. This is a technology I have not researched so I will - thank you. The internal insulation is not filling me with joy but I know I have to explore it - thanks for your advice.

Screwdriva

Kiittykatz said:

Hey Screwdriva, It is electric radiators that will be ripped out. This is a technology I have not researched so I will - thank you. The internal insulation is not filling me with joy but I know I have to explore it - thanks for your advice.

In that case, the air to air source heat pump will be far more cost effective and likely more efficient. I recommend a Daikin/ Toshiba or Panasonic as excellent brands and if you have a small number of rooms, a multi split unit will be much less imposing with only one outdoor unit. Depending on where you reside, it will also provide cooling during the summer months which is a nice bonus!

Best of all, if you have an appropriately sized PV system, it should easily be able to offset the electrical draw on most days (with insulation!). I've seen them run as low as 450 watts at 0 degrees outside!

PV should help with hot water too but I would contact Mixergy directly for a quote for that heat pump cylinder

Kiittykatz said:

The internal insulation is not filling me with joy but I know I have to explore it - thanks for your advice.

I get where you're coming from. The 55mm insulated plaster boards are the least disruptive option in my humble opinion. You'll love the difference! 

Kiittykatz

shinytop said:

Kiittykatz said:

I have bought a property that has solid walls and wish to install ASHP heating as the property currently only has electric heating. I have now uncovered all the insulation that is recommended for ASHP to work efficiently and control my electric costs. Has anyone here had experience of ASHP with solid walls that they have not insulated externally or internally. I do not wish to render the house as it is expensive and changes the appearance of the house, and the internal insulation means I lose floor space - not ideal. Interested in peoples experiences - thanks 

No direct experience but I went from storage heaters to ASHP and am very pleased. I assume you have done the easy stuff like loft insulation?  If you have, and have a relatively draught free house there is no reason why a well designed A2W ASHP won't won't work with solid walls.  You'd need appropriately sized radiators so they can work at low-ish temperatures. As @screwdriva says, it won't be cheap. Mine was £16k or so, fortunately for me mostly paid for by RHI.  

It's all about the heat loss of your house.  If youn work that out you'll get a good idea of how an ASHP might work. You could have a go at doing the calculations yourself or get a quote from a supplier, although you'd probably have to pay for that. There are a few calculators available online, shout if you want some links. 

Remember that an ASHP system will use about 1/3 of the energy your current direct electric system does.  

Thanks shinytop Yes loft insulation done. I have not used the electric heating as I have not moved in yet so I haven't experienced those bills. I am going through the toss up as to whether I go with Gas or the Air pump - very worried about spiralling electric costs due to lack of insulation. Having a look at the linsk now as I found some online. Thank you

Screwdriva

Kiittykatz said:

Thanks shinytop Yes loft insulation done. I have not used the electric heating as I have not moved in yet so I haven't experienced those bills. I am going through the toss up as to whether I go with Gas or the Air pump - very worried about spiralling electric costs due to lack of insulation. Having a look at the linsk now as I found some online. Thank you

If you go with gas you will likely need to replumb the entire residence, which will likely cost more than the boiler or air to water heat pump. 

An air to air + heat pump water cylinder will cost considerably less to install and will be heavily subsidized by solar PV when running. 

Kiittykatz

Screwdriva said:

Kiittykatz said:

Thanks shinytop Yes loft insulation done. I have not used the electric heating as I have not moved in yet so I haven't experienced those bills. I am going through the toss up as to whether I go with Gas or the Air pump - very worried about spiralling electric costs due to lack of insulation. Having a look at the linsk now as I found some online. Thank you

If you go with gas you will likely need to replumb the entire residence, which will likely cost more than the boiler or air to water heat pump. 

An air to air + heat pump water cylinder will cost considerably less to install and will be heavily subsidized by solar PV when running. 

Thanks. My roof is north facing so judging by a very quick read it is not suitable for Solar panelling (another thing to research haha). Are you suggesting the mixergy to compliment the heating and boost the water temperature? Another questions A2A or A2W - what are the differences? Thanks!

shinytop

Kiittykatz said:

Screwdriva said:

Kiittykatz said:

Thanks shinytop Yes loft insulation done. I have not used the electric heating as I have not moved in yet so I haven't experienced those bills. I am going through the toss up as to whether I go with Gas or the Air pump - very worried about spiralling electric costs due to lack of insulation. Having a look at the linsk now as I found some online. Thank you

If you go with gas you will likely need to replumb the entire residence, which will likely cost more than the boiler or air to water heat pump. 

An air to air + heat pump water cylinder will cost considerably less to install and will be heavily subsidized by solar PV when running. 

Thanks. My roof is north facing so judging by a very quick read it is not suitable for Solar panelling (another thing to research haha). Are you suggesting the mixergy to compliment the heating and boost the water temperature? Another questions A2A or A2W - what are the differences? Thanks!

A2W is a system that runs radiators and your hot water, like gas CH.  A2A is an air conditioning unit that can heat by blowing hot air, like the ones in hotel rooms or villas abroad. You need something else for hot water such as the Mixergy already mentioned. 

Note that you need specific planning permission for any A2A unit that is used for cooling or if you have more than one whether cooling or not. Most domestic A2W ASHPs fall within permitted development hence no specific permission needed. Not a showstopper but something to be aware of. 
   

I

Kiittykatz

shinytop said:

Kiittykatz said:

Screwdriva said:

Kiittykatz said:

Thanks shinytop Yes loft insulation done. I have not used the electric heating as I have not moved in yet so I haven't experienced those bills. I am going through the toss up as to whether I go with Gas or the Air pump - very worried about spiralling electric costs due to lack of insulation. Having a look at the linsk now as I found some online. Thank you

If you go with gas you will likely need to replumb the entire residence, which will likely cost more than the boiler or air to water heat pump. 

An air to air + heat pump water cylinder will cost considerably less to install and will be heavily subsidized by solar PV when running. 

Thanks. My roof is north facing so judging by a very quick read it is not suitable for Solar panelling (another thing to research haha). Are you suggesting the mixergy to compliment the heating and boost the water temperature? Another questions A2A or A2W - what are the differences? Thanks!

A2W is a system that runs radiators and your hot water, like gas CH.  A2A is an air conditioning unit that can heat by blowing hot air, like the ones in hotel rooms or villas abroad. You need something else for hot water such as the Mixergy already mentioned. 

Note that you need specific planning permission for any A2A unit that is used for cooling or if you have more than one whether cooling or not. Most domestic A2W ASHPs fall within permitted development hence no specific permission needed. Not a showstopper but something to be aware of. 
   

I

Got you - thank you!

Screwdriva

Kiittykatz said:

Thanks. My roof is north facing so judging by a very quick read it is not suitable for Solar panelling (another thing to research haha). 

Typically roofs have two aspects - nothing facing the South?