gaschick

Apologies if you have read this before - I am reposting this in this part of the forums to potentially generate some more replies! 'Hi, We live in a 5 bed detached house built in 2004 in the middle of North Wiltshire. We have just put in for planning to demolish our existing double garage as we have clay heave/subsidence in one corner and need extra bedroom space upstairs in our house. The garage would be rebuilt adjoining our house, with extra bedroom space above (to even out the sizes of the bedroom for our three children) with much better foundations! We are also going to remove an extremely draughty oak framed conservatory extension in the existing footprint with proper well insulated cavity walls and roof. Our house is just under 200m2 floor space. The new upstairs space above the garage will add about 40m2 to our foot print. We will put in UFH in the new kitchen diner room where the oak framed extension was. We have been investigating replacing our 16 year old oil fired central heating with an air source heat pump for about two years. We are obviously keen to get the new green homes grant, and are obtaining quotes for this work. Two years ago we were quoted £15,000 for a Viessman system, and we were told that we may need to replace 2 radiators. We weren't in a financial position to do this, and there don't seem to be any Viessmann installers in our area currently. Two quotes have come back for supply and commissioning only to meet the RHI standards, and one is for supply and fit. I am now obtaining quotes for the fitting of the system. I am finding it near IMPOSSIBLE to compare quotes and the efficiency of different systems. We have triple glazing throughout (green building store performance windows (value 0.85), apart from the oak framed conservatory extension. The supply only quotes both used the Mitsubishi Ecodan 11.2 kW system, and the supply and install was for the LG V 16kW system!!!! I can't see much of the maths behind to calms. One quote for the supply only has our floor area at 164m2, which seems wrong, and the other supply only has it at just under 200m2, which is right for the current floor area. Each quote has different storage tanks, and other components. The supply and fit quote was a shade over £13,000 for the LG V 16kW system. I can't understand how such different values for the best type of heat pump to meet our needs could be obtained. I am not a central heating engineer, but it does seem to be extremely difficult to be able to compare the outputs and efficiencies of the heat pumps specified. Each manufacturer reports their output data in different ways, except the SCOP values, as I understand, and the seasonal space heating energy efficiency. However, I can't find the SSHEE in all the specs! We live in a bit of a frost pocket on damp clay, and I am keen to get the maximum bang for my buck. The other issue is that Mitsubishi have run out of stock, with no prospect of anything happening before Christmas, so need to explore other manufacturers. Any advice greatly welcomed! Zoe '

Thank you very much. It's been very difficult to get any heating engineers interested in coming to look at the system with a view to installing an air source heat pump - so I think that the supply and commission only is not viable for us currently.

Thank you for your replies. We use 1200-1300l of oil per year. I have no idea really how to split this into heating and non-heating times! We currently use 2900 kWh per year on our house (we have a biodigester plant which seems to need electricity all the time). We only specifically know the U-value of our windows as we installed them! My husband has spent most of this week off work putting in extra loft insulation to get it to >300mm as we only have between 150-200mm at the present time. I don't want any arguments when it comes to the assessment of any RHI based on a new EPC.

So, would you avoid getting a Valiant ASHP? I am exploring these as alternatives to the standard Mitsubishi Ecodan as Mitsubishi have run out of product. One installer is in talks with Vaillant at the moment as he has a client who is interested in Vaillant due to the high temp outputs.

Hi, We live in a 5 bed detached house built in 2004 in the middle of North Wiltshire. We have just put in for planning to demolish our existing double garage as we have clay heave/subsidence in one corner and need extra bedroom space upstairs in our house. The garage would be rebuilt adjoining our house, with extra bedroom space above (to even out the sizes of the bedroom for our three children) with much better foundations! We are also going to remove an extremely draughty oak framed conservatory extension in the existing footprint with proper well insulated cavity walls and roof. Our house is just under 200m2 floor space. The new upstairs space above the garage will add about 40m2 to our foot print. We will put in UFH in the new kitchen diner room where the oak framed extension was. We have been investigating replacing our 16 year old oil fired central heating with an air source heat pump for about two years. We are obviously keen to get the new green homes grant, and are obtaining quotes for this work. Two years ago we were quoted £15,000 for a Viessman system, and we were told that we may need to replace 2 radiators. We weren't in a financial position to do this, and there don't seem to be any Viessmann installers in our area currently. Two quotes have come back for supply and commissioning only to meet the RHI standards, and one is for supply and fit. I am now obtaining quotes for the fitting of the system. I am finding it near IMPOSSIBLE to compare quotes and the efficiency of different systems. We have triple glazing throughout (green building store performance windows (value 0.85), apart from the oak framed conservatory extension. The supply only quotes both used the Mitsubishi Ecodan 11.2 kW system, and the supply and install was for the LG V 16kW system!!!! I can't see much of the maths behind to calms. One quote for the supply only has our floor area at 164m2, which seems wrong, and the other supply only has it at just under 200m2, which is right for the current floor area. Each quote has different storage tanks, and other components. The supply and fit quote was a shade over £13,000 for the LG V 16kW system. I can't understand how such different values for the best type of heat pump to meet our needs could be obtained. I am not a central heating engineer, but it does seem to be extremely difficult to be able to compare the outputs and efficiencies of the heat pumps specified. Each manufacturer reports their output data in different ways, except the SCOP values, as I understand, and the seasonal space heating energy efficiency. However, I can't find the SSHEE in all the specs! We live in a bit of a frost pocket on damp clay, and I am keen to get the maximum bang for my buck. The other issue is that Mitsubishi have run out of stock, with no prospect of anything happening before Christmas, so need to explore other manufacturers. Any advice greatly welcomed! Zoe