need more Data from may self installed Heat Pump

Hi there,

First timer. 

We are doing a barn conversion in Cornwall and are finally at the stage where we need to think about how we are going to heat/power it. We are not on the gas grid. 

I would like to go as green but am slightly overwhelmed by all the competing options and combinations possible. 

It’s a three bedroom property. I’m no building expert but the building has an external granite wall, surecav insulation and an internal concrete block wall. The roofs in the main will be conventionally insulated. In short I expect the EPC will be C/D? Certainly not A/B.

I was leaning for a ASHP but I’ve been told it will not be sufficient with our likely EPC. My sister has one but also they are quite loud.

I have a large south facing roof which could have solar panels, but how do they fit into things? In my experience the more complicated a system the more likely things can go wrong with the associated expense. 

I’ve only just started reading about HVO but am not sure after reading the spirited forum thread on this site. 

I do have some electrical contractors coming in the next few weeks to advise give quotes etc so I’m sure I’ll learn more, but just wanted to introduce myself. 

anyway Cheers  

SS

Hi @saecula-saeculorum and welcome to the forum.

How far on is the barn conversion?
Ie... is it too late to specify underfloor heating?

What's the roof made of?
Barn conversions usually require re-roofing. In which case, why not use a 'warm roof' construction?

@saecula-saeculorum Hi. A heat pump is the obvious choice I would say. Rather than a predicted EPC, heat loss calculations would be more useful to determine a course. Money spent in insulation at this stage will pay back over and over in the long run. If its an old stone build then moisture is a prime concern and you may have to consider carefully what type of insulation is appropriate. External wall insulation is the best choice if possible but it is expensive. Internal insulation has two routes breathable and non-breathable, lots of debate on that. If you can highly insulate floors and roof then you are 2/3rds there. If you are insulating the floors then under floor heating is the obvious way to go and works well with a heat pump. Solar panels also very beneficial 🙂

Posted by: @bontwoody

↑

Money spent in insulation at this stage will pay back over and over...

I think he means forever and ever @saecula-saeculorum  😉 

Thanks for all the replies, including the humorous ones! 😀

Its my brother-in-law who's been building it on/off over the last few years - he's very good, but we've not really discussed much the specifics of the roof insulation as it never really came up until now. Thank you for drawing my attention to the importance and opportunity here. I've been a little one-sided when thinking more about the "energy in" side. There are actually three different roof structures so I'll discuss these with him.

Some of you may be horrifed at my ignorance and apparent disinterest, but it's taken 5 years to get to this point and a degree of glaciation sets in. Now of course it seems suddenly loads of things need to happen at once! I also have no experience in building (and after this experience I will not want another!).

Anyway thanks for the tips. Much appreciated. I'll keep ye informed!

Cheers,

SS

@saecula-saeculorum we have a cottage on the east coast of scotland 60% of which is random rubble construction - effectively stone construction the remainder comprises of 2 extensions 25/35 yrs old  our main floor level is suspended 4 feet above ground level, one extension is 18 inches below ground level the other 12 inches above.

we had been heated by lpg for 35 yrs but last year we decided to take the plunge and replace the old boiler with ASHP(s) we took advantage of a 7500 grant but as our radiators were 40 yrs old and micro bore we decided to completly re pipe the whole house 5 beds 2 reception total cost iro 25k. We doubled the insulation in the roofs, our windows are all upvc double glazed and in good order. We ignored the floor insulation and read articles that state that thick stone wall are not a disadvantage and tend to act as stoppage heaters. We had heat loss calcs done and ended up installing 2x 7KWh valiant ASHPs (there was a reason for 2 and not 1 and it was simply the long delay for a 13/14 kwh unit but the upside is we do not lose heating when the hot water is running)

the whole system has now run through a 12 month cycle and has been a great success. The far end of the house is a bit cool because i run 1 zone only and the control unit is in the livingroom and set for 19-19.5 which we find comfortable being northern barbarians! It is simple to up the heat and as for hot water we have a 250 tank and the only problem we have is ensuring we don't get scolded.

costs over the year match my old electricity plus the old LPG BUT i prior to the ASHP ran a good log burner 24/7 from sept to june and this cost me 1100 a year - the stove has been on twice in the last 13 months!! So i am saving 1100 plus the extra cost of LPG over the last 12 months - i am happy with the result

we have very old SP on the roof facing east and west - it has paid for itself over 14 yrs but no great shakes but we put an 8KWh set up on a south facing field tied into a 9.2 kwh battery. Last month we used 482 units plus 127 units which were stored and released by the battery total nearly 610 units for march so if you can i recommend you apply to the relevant authorities and go ahead with solar

good luck

Posted by: @transparent

↑

Hi @saecula-saeculorum and welcome to the forum.

How far on is the barn conversion?
Ie... is it too late to specify underfloor heating?

What's the roof made of?
Barn conversions usually require re-roofing. In which case, why not use a 'warm roof' construction?

-- Attachment is not available --

 

Hi there - we are looking at underfloor heating. As I say there are x3 different roof segments - I'm not sure what the insulation specs are but will ask my brother-in-law. We haven't gotten around to discuss insulation specifically.

Will ask about warm roofing.

Thanks!

@sapper117 Hi and thanks for detailing your experiences. I really appreciate it.

The learning curve feels steep right now but I'm up for it!

As I say there are some companies coming over the next 2w so I'll no doubt revert to you guys to see what ye think re: their advice.

Out of curiosity how do you find the noise levels of youe ASHP?

I suppose the other possibility we have here in Cornwall being on granite is a GSHP, but it seems the cost of drilling down is pretty prohibitive.

SS

Posted by: @saecula-saeculorum

↑

I was leaning for a ASHP but I’ve been told it will not be sufficient with our likely EPC.

This is a heat pump myth. Both the building and the heat source are agnostic - they don't know about each other. Put another way, a kWh is a kWh, wherever it comes from. What isn't a myth is that old leaky buildings always cost more to heat, whatever the heating system.

I'm just coming to the end of my first full heating season with an ASHP heating house and hot water, not solar or any other input. By and large it has been a success, house at the right temps most of the time (why it isn't when it is cold outside is another story), and energy use in kWh about what it was with oil CH (no mains gas here either). Of course, with ASHP efficiencies of about 300%, and oil at say 80%, I should be using about a third to a quarter as many kWh as I used with oil, but I am not. This is a conundrum that no one has managed to explain: with oil, my house ~12kWh of oil per year, and stayed warm with ~9.6 kWH delivered per year; with the ASHP it also uses about 12kWh per annum, but that means, in theory, at 300% efficiency, it is pouring 36kWh into the house per annum. 9.6 vs 39 kWh - it doesn't make sense.

Mars (editor-in-chief of this forum) very kindly asked me to write an article for this website about old leaky buildings and ASHPs, you can read it here. 

@saecula-saeculorum I had a 5kw Ecodan in my last house and it was whisper quiet. Im just about to install a 5kw Samsung in my new house so I will let you know if its any different but i anticipate it wont be given Ive seen a video of it in action.

@cathoderay Great article with some great insights - Really helpful.

Many thanks.

SS