Keeping your home warm / heating / energy crisis / insulation etc

45deg flow temp design at -2deg outdoor temp is completely fine, I don’t know why @Soul was put off by that honestly?!

All the big energy companies design their systems to a 45/50deg max flow temp to cover their arses… It’s fine, it’ll only ever reach those flow temps on a couple of days in deep winter.

My system was designed to the same 45deg flow temp, and for the last month has given a CoP of 6.5 and half the estimated energy usage to keep the entire house at 21deg.

We don’t need planning permission so that side is simpler for us.

Neither do we. It didn't stop them wasting a month of time insisting we did... twice

Oh dear 🙈

Yeah its different in Scotland. I'm going down the ASHP route next year, and the reason for the delay is that I have to install internal insulation on sloped ceilings as it was flagged in the EPC. Scottish Gov will not release funds until my post ASHP installation confirms those measures have been taken.

Its a little frustrating but overall its probably something I should do, I just wish I didn't HAVE to do it to get an ASHP as my current heating system is a bag of shit.

I'm going to have to think about new radiators in places soon, ours are old and we're likely to kick off some work to our living space over the next year which will involve moving & replacing them.

If I want to be heat-pump-ready is it just a case of doing the BTU calcs for the room based on a lower Delta T and making sure they're plumbed in with 15mm copper back to the manifold?

It’s also well worth checking out https://www.visitaheatpump.com/ and visiting a similar house to yours.

Anyone’s welcome to have a poke around ours: https://app.visitaheatpump.com/hosts/441

You can do a free heat loss calculation on the Heatpunk website; this will tell you your thermal losses per room at a given outdoor temperature, which you then use as a basis for calculating radiator specs.

Pipework primaries should ideally be 22mm, with short 15mm tails branching off to each rad.

Note: the ubiquitous fancy ‘column’ style rads that look nice are all bullshit, and don’t output anywhere near the BTU that the retailers claim.

yeah, this was my understanding about column radiators, which is why I need to get it sorted relatively soon as it'll have a knock on to layout. oh, wait, by column rads you means the faux cast iron types rather than just vertically orientated? I can think of a couple of spot where vertical rads could go, but horizontal ones will require compromises in the layout/position of them.

By the way, did you go for UFH on your place, or just rads? Any floor insulation? I think it's Victorian right, which would mean suspended floors?

I mean the ‘column’ faux iron style, as per the attached pic. They come in all sorts of shapes, including vertical. They’re all fake news with regards to actual vs quoted heat output, and vertical rads are much worse than horizontal due to convection and fluid dynamics.

We have wet UFH in the new kitchen extension and the upstairs bathroom, rads everywhere else. Couldn’t afford to install UFH in the living room, as to make it work effectively you’d need to completely replace the suspended floor with a filled-in insulated slab and screed. Every house I’ve been in with retrofit UFH between joists in a suspended floor has felt sub-optimal, requiring high flow temps and not retaining heat as a slab & screed would.

We insulated under the floorboards in our living room with 150mm mineral wool.

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See this is the myth “not working in old houses” but you’ve not really answered my question.

I know 2 people with badly designed systems that are constantly moaning about bills with a HP.

As you know I’m a gas engineer but tbh I’ll fit anything if it works and I know they work but to get it done right it costs money and they money vs the cost of an equivalent gas boiler is huge.

It’s really like comparing apples and pears let’s face it.

On the cost issue: our ASHP system was a couple of grand cheaper than the lowest quote we had for a gas boiler system. Post-grant, of course.

Your friends with poorly-performing systems may just be running them in a way that’s inefficient (programmed to operate like a gas boiler). It takes will to understand why a heat pump system needs to be run differently, and break old habits.

We have wet UFH in the new kitchen extension and the upstairs bathroom, rads everywhere else. Couldn’t afford to install UFH in the living room, as to make it work effectively you’d need to completely replace the suspended floor with a filled-in insulated slab and screed. Every house I’ve been in with retrofit UFH between joists in a suspended floor has felt sub-optimal, requiring high flow temps and not retaining heat as a slab & screed would.

This might be the deal breaker, as I think at the very least (to get it work efficiently as you describe) we'd need to break out the solid floor and insulate, even with no UFH. I need to look into costs I don't mind doing some of the grunt work, but I'm under no illusion that it'll be cheap. Of course it'll bring benefits what ever heating system we use and surprisingly my wife is quite up for spending money on it, but as I say, we've not had quotes yet. Will need to level for existing floor anyway so I guess that's a small saving.

Do you know what your current solid floor build-up is? What kind of house?

1980s, solid floors, I'm assuming no insulation, but need to look into the regs at the time to get a better idea. Any ideas where to find that info? I don't know where to start!

EPC, speak to neighbours, drill a core sample… profit?

If you don’t mind losing a bit of head height, you could always overlay with 100mm PIR then pour screed over wet UFH. Or just get nice, cheap & effective big rads…

ceiling's 2350 so I don't think that's a route I really want to go down, as tempting as it is from the ease of installation perspective.

#henchrads

our ASHP system was a couple of grand cheaper than the lowest quote we had for a gas boiler system. Post-grant, of course

I'd be really interested to see the cost breakdown for the two options. Including the new radiators, fabric upgrades etc (and which of them would have been "needed" for which scheme).

Anonymoised/ballpark fine of course, and obviously if it's too much of a pain to collate then no worries.

When I eventually do some work to my own flat, I want to avoid abortive work. Of course I want/need to control costs but I don't want to have to redo work in the future just because I locked down the budget too much.

our ASHP system was a couple of grand cheaper than the lowest quote we had for a gas boiler system.

I guess it depends if you're doing a full refit. Our replacement boiler was £1,700. What's the cheapest you could install an ASHP grants and all?

I'm going down the ASHP route next year, and the reason for the delay is that I have to install internal insulation on sloped ceilings as it was flagged in the EPC

Thanks for confirming this. Sounds frustrating but understandable and probably sensible overall as you suggest. Hope it goes smoothly when it comes to the install.

This prompted me to look back at my own EPC. Frustrating. The recommendations are:

Internal or external wall insulation.
Insulation under suspended floor.

The annoying bits are that external wall insulation is obviously a nonstarter because the building is in a conservation area. Internal wall insulation might make sense, but the report assumed everything was plastered on the hard, whereas all the walls are actually dry lined (usually lath and plaster, but modern stud/plasterboard/rockwool to one of the kitchen walls).

Insulation of the suspended floor is reasonable and I want to do it, but the report missed that the kitchen floor, bathroom floor and part of the hallway are engineered timber directly onto some kind of slab.

I'm assuming that a new EPC (by someone who is paying attention and understands how the building is actually put together) would help. For example I wouldn't mind insulating some of the walls internally, but the benefit is not so clear on every case - e.g. some walls are in permanent shadow, some get sun externally, some are sheltered and some have the prevailing wind (of which there is a lot!). A considered approach feels reasonable, but if I was forced to insulate every wall then I'll lose that thermal mass, the redecoration costs would be prohibitive, and I'd still have heat loss from the lack of air tightness on the west-facing wall.

The home energy Scotland website implies that they'll do custom reports for some situations - did you look into this at all?

Sure!

Our situation was that we had to rip out and completely replace the entire heating and plumbing system, including all radiators and pipework, as it was all ancient & fucked, none of it re-usable, and the boiler etc was in a part of the house that had to be demolished anyway.

Gas: Vaillant system boiler, 250l Vaillant unvented cylinder, all controllers & ancillaries, all new plumbing, all new rads and UFH designed to 50deg max flow temp. Quotes we had for this gas system ranged between £6K and £7K, excluding rads/UFH.

ASHP: Vaillant 7kW ASHP, 250l Vaillant unvented cylinder, NO BUFFER VESSEL (kills efficiency), all controllers etc, all new rads and UFH designed for 45deg max flow temp. We ended up paying ~£3.7K (exc rads/UFH) in total for this, obvs including the £7.5K BUS grant free money which the installer dealt with entirely on our behalf.

So in our specific case, at least £2K cheaper than an equivalent gas system. Our builder ended up digging the trench for burying the external flow/return pipes for the ASHP and constructing the slab for it to sit on, which saved the £5K cost that the installer wanted to charge for this, but this is basically aesthetic and not required (can happily run the pipes above ground). We also deleted the buffer vessel from the original design, which is completely unnecessary and hinders performance, which saved another ~£1K.

Rads/UFH: as both systems were designed for a similar max flow rate, the cost difference between rads sized for 45deg vs 50 was negligible, and the UFH was similar (100mm pipe centres as much as was possible in both cases). We had a couple of different plumbers install the UFH, rads and pipework around the house to a spec dictated by the ASHP designer, as again the quote from the ASHP installer to do this was unaffordable.

The actual rads, copper piping and pipe insulation etc were all purchased via the ASHP installer as part of the install job, saving the VAT.

A relative had their Daikin ASHP system installed by British Gas for ~£1.5K all in, but they didn't need to replace any rads or pipework.

A lot of the self-build community buy all the bits themselves and have their systems installed by a friendly local plumber on a day rate basis, then claim the £7.5K grant via an 'MCS umbrella scheme'. Haven't read up much on how that actually works. This way, it's apparently easy to end up with a system that costs almost nothing.

FWIW I don't think the EPC recommending EWI/IWI is enough to stop you from getting the grant. IIRC they recognise how expensive/disruptive that would be.

Radiators don't cost much but redecorating where you've had to move pipework, etc costs a lot.

The theory on the temperature flow thing is interesting, maybe I'll give that a try by turning the boiler down and see what happens over the course of a day. Bringing the house up to temperature when cold takes a lot of boiler on time but I'm not sure what cooler flow would be enough to offset the temperature in the cold months.

Although I'm still not sure where I'd actually put a heatpump, they look massive in all the pictures.

Most efficient and lowest-cost way to run a heat pump is: it stays on, the entire time, forever, all year round, 24/7/365. An outdoor sensor (weather compensation) constantly modulates and adjusts the flow temperature so that your house only receives the exact amount of heat energy required to maintain it all at your chosen internal temperature.

There is no longer any concept of a "thermostat" or "bringing the house up to temperature when it's cold". It always just stays at your chosen temperature, all the time, because the heat pump is on and running the entire time. You can, of course, program lower 'setback' temperature periods overnight etc, it's up to you.

Avoid any kind of zoning, 'smart' controls/TRVs etc. Turning off the heating in certain rooms costs more to run than just keeping the entire house bubbling.

You can visualise an external unit with your phone here: https://www.pumpchic.com/#test-drive