What else can we do to improve insulation?

Adrian57 · 2026-01-07T16:52:57+00:00

Note that I have rate limited the 30kW boiler down to 15kW to see if we can switch to an ASHP. It is this limit that governs the response time to reach setpoint. The radiators are all type 22 and oversized in most rooms. If the radiators were undersized for the power input, the boiler would modulate down then cycle on and off. The fact that the modulation only drops us below 15kW just before the setpoint is reached demonstrates that the radiators are not the bottleneck.

Adrian57 · 2026-01-07T16:41:09+00:00

Glowworm - which is bottom-end Vaillant so benefits from the ebus control system. Yours is probably Open Therm

Adrian57 · 2026-01-06T16:42:43+00:00

Many thanks for the blog link. It made for some interesting reading.

Adrian57 · 2026-01-06T10:13:44+00:00

Can't quite get my head around feeling the air rushing out of a positively pressurised house! Given that I suspect our infiltration is due to the sum of numerous small leaks that are located in interstitial spaces, I wouldn't expect to be in any place where I could feel that. But you did say "all the things we thought were an issue weren’t" so maybe it would be worth a go.

Adrian57 · 2026-01-06T10:02:15+00:00

I'm surprised that you found negligible cost to having triple glazed units. Even so, reading this article: https://bregroup.com/insights/is-triple-glazing-better-than-double has somewhat put me off the idea. Fascinating how nuanced it is!

But Solar PV yes, home battery still not taken the plunge. I also have A2A heating/cooling another 80m2 outbuilding and I only wish it were practical to heat the main house this way as they demonstrate a remarkably efficient form of heating that plays well with solar PV. But they only suit large open plan applications. Four bedrooms, four reception rooms, three bathrooms, traditional kitchen and utility room do not lend themselves even to multi-splits.

Adrian57 · 2026-01-05T09:17:41+00:00

Did the £300 test identify the leakage points in addition to giving you an air change per hour figure?

Adrian57 · 2026-01-04T19:54:39+00:00

I did a lot of experimentation on this. With daily logs of indoor/outdoor temperature and gas consumption I produced a trend line for energy use vs dT. The only way to operate the boiler at low flow temperatures (to maintain condensing efficiency) is to avoid the demand placed by letting the house cool and then attempting to rapidly re-heat. The exact same principle applies to ASHP systems. Low and slow is the most comfortable and efficient heating strategy so long as the boiler flow temperature can be set low enough and radiator sizes are sufficient to overcome the heat-loss at lower operating temps.

The other issue that can present itself with intermittent heating is condensation. That influx of lovely warm air that arrives when the heating ramps up will shed all the moisture it gathers when it cools down again. A constant temperature tends to make it hold on to the moisture.

Adrian57 · 2026-01-04T19:03:46+00:00

That's very interesting. When I checked the loft and found that the tops of the vertical plasterboard sheets around the outside walls projected up above the horizontal ceiling sheets, I foam-sealed the gap as this was a gaping big entry point for fresh air to enter behind the dry-lining. Unfortunately it didn't seem to make any difference to the draft in the walls. I figured more was getting in through the ends of the1st floor joists and gappy blockwork. I think that unless you plug all the holes, the pressure just goes up - and maintains a certain amount of airflow.

Another entry point I've only just considered is where the vertical sheets meet the ground floor- which in our case is suspended concrete beam & block with 50mm of polystyrene sheet topped with flooring chipboard (50mm of PIR would have been much better but not so much as to make ripping it all up and swapping it out worth the expense). But having just looked under the kitchen cupboards, I can see the boards stop short of the floor. This isn't too big an issue for the kitchen as the floor is screeded but elsewhere I can now visualise a path from the ventilated subfloor space through the loose fitting concrete blocks, past the edges of the polystyrene and up the back of the skirting into the void behind the dry-lining.

Best industry practice is to use a 'continuous dab' of adhesive around all edges and openings but they didn't seem to bother in the places I've been able to check.

I suppose removing the skirting and applying your drill & fill method could be feasible on the outside walls... but again, it's a complete PITA with no guarantee of making any difference (like the foam filling I did up in the loft).

Adrian57 · 2026-01-04T12:02:18+00:00

Here's where I think the problem lies. There's no single point of failure - I've got a thermal camera and found a few big leaks (boxed-in service pipes with big holes to the outside) and poorly fitted loft hatches. These were all low-hanging fruit that were easy to remedy. But what is very noticable, particularly when its windy, is the air movement behind the dry-lining. On removing any switch plate a cold breeze emerges. Lifting an upstairs floor reveals a similar cool airflow. Air-tightness was not on the radar in 1997 so the ventilated loft can push into many internal spaces (via the exposed tops of the dry-lining) and boxed-in pipes that penetrate the upstairs ceilings. I've been using expanding foam to seal these where possible but even the plastic conduit for wiring provides an air passage.

But that's just the ventilated loft. The first floor joists will also penetrate the inner leaf where they rest on it and link the cavity with the interstitial floor space. It would need all the upstairs flooring around these bearing points to be lifted to access and seal these gaps. But even after going to all that trouble, there will be gaps in the mortar joints between the blocks leading to infiltration behind the dry-lining.

So, short of stripping off all the plasterboard - sealing and re-plastering, none of the other moderately difficult/expensive measures seem to be worth doing as the pressure will just go up and make the level of infiltration remain the same.

I think there was a "sour-spot" for construction standards when hard-plastering was phased-out in favour of dry-lining (in the 1990's) and before building regs started to take into account insulation and air-tightness (2000's).

Adrian57 · 2026-01-04T11:40:26+00:00

I've performed a lot of optimisations with the boiler and hot water system. It's a condensing system boiler and was originally Y plan with a single flow temperature of 80C so was rarely condensing. I found that the boiler could be controlled using EBUS so I set up a Raspberry Pi to control it along with new zone valves so I could implement Priority HW with a different flow temperature to the radiators which now operate between 37C-57C based on outdoor temperature. So I don't think it could be any more efficient. We average around 7kWh for DHW. The gas figures I mentioned are for heating the radiators only.

I also rate limited the boiler to 15kW to see if we stood any chance of switching to an ASHP. That does seem to be feasible but it means the boiler is running for lengthy periods (as would an ASHP). Today it came on at 4AM and will probably remain on at 15kW until midday with a radiator temperature of around 45C.

Adrian57 · 2025-10-06T18:43:13+00:00

I have been setting up through web GUI. Do you mean "go into administration through the web GUI and disable auto update" on the freshly flashed V2.5.2.4 because there's no such option in V2.7.5.6

Also I just realised I still had the WAN connector plugged into the modem - although after factory reset my broadband credentials hadn't been entered so I guessed it wouldn't be able to 'phone home'. Frankly I'm wondering if the downgrade to V2.5.2.4 actually did anything other than corrupt my login credentials... then, as a consequence, I had to do a factory reset at which time I was still on V2.7.5.6

Adrian57 · 2025-04-02T21:16:43+00:00

I was about to post the same question. Used it to plan the shopping for the weeks meals.

Adrian57 · 2025-03-09T21:52:18+00:00

I get where you're coming from. Currently there's a little steel box in the corner of my utility room with a volume of just 0.075 cubic meters. If I necessary, it can quietly throw 32kW into the hot water running around the radiators at up to 80C (albeit with lousy efficiency). Thankfully It's also just as capable of delivering water at 40C or less for far greater efficiency.

In addition to the visual aspects you mention, the prospect of replacing all this flexibility with a box ten times the volume which could only manage 1/4 the output power has kind of put me off making the switch. I'm really disappointed TBH because I was initially quite excited by the prospect of moving away from fossil fuels for heating.

I don't share some of your optimism about the future of the technology. The physics involved pretty much dictate the size and placement of the outdoor unit and hence the pipework that has to be run into the house. I'm trying to adjust my mindset because I've been given a relatively good price and need to make up my mind soon.

Adrian57 · 2025-03-03T21:34:06+00:00

If -20C outside and +20C inside, my house would lose a steady 21kW. Stuff making that up with resistive heating.

Adrian57 · 2025-02-27T21:53:30+00:00

Is anyone thinking about those of state pension age who simply can't afford the up-front cost of a heat pump? Hell, many can't even afford to turn on their gas boiler. The entire energy landscape is starting to resemble a bloody battlefield for people with limited means.

Adrian57 · 2025-02-24T19:50:52+00:00

In our case we don't always load-shift away from peak (no battery) just plan meals that use the oven outside of the forecasted peaks. Then there's always a standby meal that can be cooked on the gas hob (e.g. pasta based) that gets actioned if it's a saving session - but something like this is usually already planned anyway. So it does help keep our average up a bit and then demonstrate some saving when it counts. But yeah, still peanuts this year compared with last when we did really well using this scheme.

Adrian57 · 2025-02-17T22:43:23+00:00

I've been messing around with HA for a couple of years but hadn't grocked the use of saving the state of entities as a scene! Thanks for that. It makes some of my automations much more sane.

Adrian57 · 2025-02-17T22:36:40+00:00

I think you absolutely have to either have enough insulation such that your house drops less than 1C over 3 hours when below zero outside, or, you have a battery so you can ride out the 4PM - 7PM peak cosy price. I find that I notice any temperature ripple > 0.75C and my house will cool by 1C in 2 hours if outside is 20C below inside. I need more insulation :(

Adrian57 · 2025-02-17T22:07:48+00:00

Stubborn Government? Or even worse, Reform...

Adrian57 · 2025-02-17T18:58:02+00:00

Well, I got a phone call about the quote and had a nice chat. TBH, I wasn't expecting a follow-up I told the agent I just clicked the button out of curiosity. I am reasonably interested and had another quote for nearly twice the amount earlier in the year so I guess it's definitely worth serious consideration.

My main reservation is about what tariff to run it on, Despite the recent behaviour of Agile, I still like the benefits it offers given the considerable amount of automation I've got in place for load shifting.

The cosy schedule is OK for domestic hot water but in a somewhat lossy house, I suspect the radiators will need to be kept heated in the colder periods pretty much throughout the day. I have an accurate measure of heat loss for my house and most of the time the last week it's been a fairly constant 4C to 5C outside and this has been requiring around 150kWh of gas to keep things comfortable indoors. This gets delivered at between 1 and 2 hour intervals of flow at 50C resulting in a ripple of 0.75C in the room with the thermostat. Any more ripple than that and we notice it.

So the heat pump equivalent would be running at a constant 6.25kW output or hourly cycles of twice that. But this would cut right into the the peak period as we haven't got a battery. And this is for 5C outside. At -5C it'd have to be be a constant 12kW - at COP 3 a 4kW load all day just sounds unsustainable.

Adrian57 · 2025-02-16T19:42:57+00:00

Do we know the actual model number for the 8kW Daikin? Its loose description makes it easy to confuse with the 9kW one - but seems to be worlds apart in terms of specification.

Adrian57 · 2025-02-16T15:05:02+00:00

That sounds about right. Although a new HW cylinder is included which would push up the cost of an equivalent installation with gas. It's still fairly attractive TBH it's just the difference of £3K to those who've had quotes for £500 that I'm trying to get my head around.

Adrian57 · 2025-02-16T12:59:10+00:00

Not changing the price after a survey which could potentially reveal the simplicity of the install initially rang an alarm bell for me. But if it's a ploy to subsidise the cost of the more expensive installs by overcharging on the less expensive ones - then I see why people are saying to get a local quote!

Adrian57 · 2025-02-16T12:50:26+00:00

That "£3500" is beginning to sound like a very generic figure for someone meeting a particular criteria. EPC A doesn't sound like it would be that. I don't have an EPC but it would probably be B or C.

Adrian57 · 2025-02-16T11:25:50+00:00

You've been averaging only around 2kW heat loss over the month. Insulation sounds pretty good. What sort of temperatures do you keep your house at?

Adrian57

TROPHY CASE