@jamespa I had one company design at 55 because I was struggling for radiator space... I've had others pull out because I couldn't heat the room properly without additional inputs.
I'd like to design to a 35 or 40 flow temp. 55 is what my combi currently runs at but I can't hit 21 in this room, only 19.5.
Fair enough. Obviously you understand that you will take a running cost hit but all designs are a trade off. 45 is often a good compromise for radiators and, with a properly designed system is sufficiently low that the running costs should be no more than gas, possibly a bit less.
By properly designed I mean one with no buffer tanks, low loss headers, plate heat exchangers for 'system separation' and no external controls or thermostats (other than possibly trvs on a small minority of the rads or controls like homely which are very specifically designed for heat pumps).
I would consider a fancoil if this is in a living room.
This post was modified 3 weeks ago 2 times by JamesPa
4kW peak of solar PV since 2011; EV and a 1930s house which has been partially renovated to improve its efficiency. 7kW Vaillant heat pump.
@jamespa yes thanks, I've been quoted a min SCOP of 3.60, so as long as I could get cheaper electric than 22p I think it starts to pay it back. Another reason I'd like to find an alternative, cheaper installation. Which is why I wanted to reduce conservatism in the heat loss calculations, which is where I started in this forum.
This room is an open plan kitchen/diner/lounge, I'll dig deeper into a fan coil radiator.
One installer quoted £8,000 for the downstairs to be wholly UFH...
Currently cost, the initial outlay, is the biggest road block to getting an ASHP for me.
what’s the floor area for that quote, out of interest?
I was recently quoted about £6k for 100m2 (whole ground floor) or £3750ish for 57m2 (just the solid floor)…but there are extras on top such as some plumbing work, and it doesn’t include the flooring
i haven't ruled it out yet but I think the decision will be made at the end of the project…assuming it’s not a decision I have to make from the start
1. A house which doesn't have an operational foul water system is uninhabitable, can't be sold on the open market, and may be uninsurable.
It's the most basic of the checks which should be done by a surveyor acting on behalf of a prospective purchaser.
Building over a live sewer is a no-no, and should've been picked up by Building Control Officers, and the Planning Dept when those drawings were submitted. It would usually be dealt with as a Planning Condition, whereby its relocation is a requirement of consent being granted.
2: I can immediately see that the standard of building work to construct the conservatory matches that which we've come to expect from companies installing heat-pumps.
Ie the 'standards' haven't been implemented, and the work is of poor quality.
At this rate, @editor will need to start a whole new section of this forum to address Building Works! 😥
The To-Do list:
A: You absolutely need to establish where your home's foul water pipes run, and whether you have responsibility for ensuring sewerage pipework for your neighbours.
Start with the 'new' inspection chamber 5m away, lift the cover and see where it's flowing from/to. Get someone else to flush a toilet and check if your own house is connected to it.
Start adding this information to a copy of your plans.
B: establish what those pipes do which are already disappearing into the concrete pad.
C: Those electrical sockets are too low. They should be 400mm above Finished Floor Level (FFL).
Open them up and let's see where the connecting wires are running. We don't want to see them going downwards into the floor!
D: Is the kitchen gulley still operational and visible within the conservatory?
E: I doubt that the company who can cut slots in the floor would be prepared to work around the existing inspection cover.
You really do need to see what's below it. I bet I could lift it with a pneumatic drill!
I’ll reply to your numbered points, I appreciate it’s been a long time but I’ve been juggling a lot recently
1. I think I queried this with BC before we tiled over it, I also queried the soak away and in all honesty they didn’t seem to know anything about any of it. They were knowledgeable with regard to BC rules and regs, just no data, paperwork etc to refer to for my property, or so it would seem. The work was done in 2007, we bought the house in 2018, so it got past our solicitors…and planing/BC didn’t seem to know much about it when I asked. We definitely have a fowl water system, the stack runs up that corner of the house, I’m not sure if it’s combined rainwater and fowl water here or not
2. Yep! It’s not just what we inherited, that made me think I have nothing to lose by DIYing as much as I could, and teaching myself off the internet, but also the quality of work we paid for has been shocking as well. And to add insult to injury a lot of the work wasn’t even completed to what we asked for.
A. I haven’t done this yet - but I will.
B. The vast majority of copper you can see in the last pic I posted with the unfinished tiling, was all installed with our new boiler, so that’s all heating and hot water, plus a random hot water inlet and cold water inlet. The plastic is all for the utility sink & dog shower, which pass through the wall to the WC and that’s where the soil stack is
C. Yes they are ridiculously low. I can’t remember where the wires run, but I know we had a fault a couple of years ago which was traced to the socket on the left you can see in that picture, and a socket across the other side of the room. The wiring doesn’t pass over the 2 doorways on its way to the next socket…so the conclusion was that there is wiring running under the concrete floor and that the break was there. It was isolated and we ran the other sockets off a separate socket loop from the main house…but what a mess.
D. The kitchen drainage is boxed in, in the conservatory and is behind the sofa. It looks crap! We’ve never unboxed it because I daren’t look, but that all runs under the concrete conservatory floor…
E. If I come to lift those tiles I will try and have a look. They came out and said they’d be happy to just plan the loops around it…
1. Sadly I would say the standard of work is exactly what one expects, this is either the building trade and/or quite possibly in part DiY, and the use of the extension is/was somewhat subsidiary to the 'main' house; just from casual observation poor construction seems to occur frequently in these circumstances.
2. Sockets at the level depicted are very common, I would say (from casual observation) more common that sockets higher up (just because of the age of our housing stock). I don't know when it became a requirement to locate them higher and to what extent that requirement applied to extensions.
3. Combined drainage, where foul and surface water route to same drain, were the norm until (I think) the 1970s. I dont doubt that, where combined drainage exists, new surface water drainage eg from an extension gets connected in whether or not it should be.
4. As @transparent says the integrity of the foul drainage is paramount and should definitely be checked!
hi, again apologies for the delayed reply
1. Good guesses, I expect you’re quite accurate, we are ready to try and make it more inhabited hence the desire to indulge it and heat it properly! I hate jobs that aren’t done ‘properly’ with cut corners, unfortunately that’s what this house is and at the risk of generalising, I’ve struggled to find a trade in the south so far who isn’t part of that problem
2. We changed all the skirts to more modern ones…didn’t realise at the time that the sockets were so low and on a couple we had to even cut them sockets into the skirts which looks awful. One day I’ll move the sockets up and fix it but you move one, you’ve got to move them all…
3. It’s a 1972 house so I reckon it could be combined. My only real doubt is that the river gamble runs past us and into 2 large ponds in the village, which are also filled by local rainwater…or so I believe. That would imply you’d need a separate fowl water system. Maybe I’ll look more into that
4. I will look. I’m recently out of hospital so heavy lifting isn’t on the agenda for now but I’ll at least have a look tomorrow and order some drain keys if I think I need them - we replaced the cover with a block paved one so it’ll be pretty heavy
@sicky -- please don't be daunted by any of the above. There are a number of options to resolve the issues of foul-water drains, depending on what you find.
Nor are they particularly expensive. Underground drainage components are pretty cheap when you look at the overall renovation work. A 3m length of 110mm diameter pipe is about £14, and an inspection chamber, risers and cover can be bought for less than £100.
There's nothing to prevent you doing (the majority of) the work yourself... ... and you certainly don't want to be paying a qualified tradesman just to dig a hole!
I have a 'live' sewer running beneath my extension, for which I took advice from the local Building Control officers (who aren't actually meant to do so!).
I placed new inspection chambers at each end of the run, and ensured that there were no joins/elbows actually beneath the floor.
Here's the downhill side, where you can see the cover of the inspection chamber, and a couple of spare 'riser' rings. These allow me to set the height of the concrete cover once I've worked out where the finished ground level will be.
The building trade may take short-cuts and fail to properly install stuff, but self-builders don't.
We're hardly likely to compromise the standards on our own house!
Building Control surveyors know this. Once they've assessed our work on the first of the 14 main check-points, it's unlikely they'll bother to attend on-site again!
This Forum will continue to advise you as you wish. Just keep us informed of what you find.... preferably with an accompanying photo.
@editor and I can split this out into a separate topic, so please ignore the Topic Title and keep posting.
the issue with this is…on the earlier drawings, if all those drains and gulley run into that one manhole, which is now under my concrete floor and also under tiles…how do I access any of that to add inspection chambers, and where would I put them?
I can’t think how I’d access them from outside of this either
the only thing I can think of…
…the garage annex had an en suite installed. The toilet, sink and shower wastes all run straight out of the wall and into the ground outside of the house…just outside the utility room door. I imagine they also run to the same manhole.
maybe they could also be used for inspection if ever required?
i don’t think my Mrs will ever sign off on taking everything out of the downstairs to do it….kitchen out, toilet out, more new flooring, remove fireplace…then put kitchen and toilet back again
@jamespa yes thanks, I've been quoted a min SCOP of 3.60, so as long as I could get cheaper electric than 22p I think it starts to pay it back. Another reason I'd like to find an alternative, cheaper installation. Which is why I wanted to reduce conservatism in the heat loss calculations, which is where I started in this forum.
This room is an open plan kitchen/diner/lounge, I'll dig deeper into a fan coil radiator.
I remember thats where you started (conservatism in heat loss).
What do you actually know in total about heat loss. Do you have any consumption figures for past years. FWIW my house was rated by two surveyors at 16kW (full three hour surveys in each case). Doing the calculations properly using MCS assumptions gives 10.5kW. Its actually 7kW, so, if my house is anything to go by, you are right to be cautious about loss figures. I collected a fair few figures together to size my installation.
One final option which might suit you is adia thermal. They fit meters and special heads on the TRVs allowing them to measure house and room loss, and optimise the flow settings. One of their ideas is that you do the ashp installation in 2 stages, ASHP first then rads, rads only after you have collected lots of measurements to determine which rads actually matter.
@jamespa I have approx 20 months of gas energy usage. DHW usage is limited, occasional washing up, baby/toddler baths and occasionally showers. We had a broken shower door in one bathroom so used the other electric powered one for 18 months till I got time to fit a new one.
Aug-Dec 2023 was 3135 kWh, 2024 was 6,750 kWh and 2025 so far is 443 kWh. I guess that's in line with a 7 kW heat loss at 21 degrees rather than the below 6 I see to keep it at 18.
I have reached out to Adia, hopefully they find my project interesting enough to pick up during their development stages!
@lakey Do you have half hourly or daily readings and what was the heating pattern. Basically my ashp was sized on gas meter readings and the fabric spreadsheet was 'adjusted' to fit.
@jamespa yes I think I've downloaded half hourly from Octopus, I think they gave it in gas m3 though...
I can't be certain of the exact schedule as I have constantly tweaked start times/temperatures slightly. Basically we run it at constant temperature approximately 18.4 set point now and on from ~6am till 8pm with a set back of 15 or 16.
There may have been points where we kept this at 17.5 or something through the day, or had it come on an hour later in the morning depending on the kids wake up time!
How did they adjust the fabric sheet, by just ensuring the total output from the radiators in the house balanced the total heat loss/energy usage even if room by room it didn't match?
My boiler is a 2005 condensing boiler, so while theoretically reasonably good efficiency the previous owner did not get it serviced.
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