Andeh

The telegraph is toxic these days, their anti-heat pump and anti-EV bias obsession is ridiculous!

Thank for all the comments here, our setup is decidedly awkward & hard work to manage! ASHP feeding 2 x UFH Manifolds with no blending valve but we are over zoned thoughout (lesson learnt here). Every room having its own stat - 22 of them throughout the house. Due to a c290sqm bungalow and 2 x mono pitch roof we also see very different temperatures throughout the house because of very 'odd' rooms...small floors & high ceilings etc etc This means we have 3 bedrooms which are relatively small floor space with very high ceilings - because they each have a mezzanine & staircase in for sleeping 'up stairs'. Floor being carpeted means these rooms are always 15% colder then the rest of the house based on the small floor vs volume of air inside. Blending valves do not make enough of a difference to balance these rooms vs rest of the house - probably due to our manifold being 11 zones on one pump & flow rates being bottle necked. A night time setup of 2 degrees & operation 24/7 would have these 2 rooms short cycling the ASHP all night & rest of the rooms only needing 1 top up a night. That being said on average nights - mid single figures no real issue. 2 x 4 hour chunks sitting in the Cosy periods is enough to keep all rooms at 20 degrees and the 'cold bedrooms' around 18 degrees during daytime and a degree or two lost over night. On very cold nights we need to run for c10 hours to achieve the above, then see temps flow as you'd expect. All of this is done with a flow rate of 28-32 degrees, hence debating flat lining the flow rate at 37 degrees during Dec/jan to keep us warm during the day & maximising cosy cheap rate of 16p and dumping more 'raw heat' into the slab to coast through the real cold snaps. I have lifted up the Weather comp from 2 degrees to 4 degrees (i think).....would a compromise be to lift it up to say 6 degrees? I presume this would lift the flow rate up a few more degrees on the low end, but still have a sort of weather comp to help efficiencies on milder days?

We run a Samsung Gen6 ASHP and despite having a 'well' insulated house (very good vs average new build, 'good' vs BuildHub standards) it is still a challenge to really warm up - caused by it being a sprawling bungalow with very very high ceilings (3.5 to 4.5m throughout) and carpeted floors. It was fine during the last cold snap we had (3-4 days of -3 temps) but we needed to run the ASHP all day to keep around 20 degrees, and at night it froze up so we turned it off and only ran it al day. With our current setup we run all zones together, to maximise the 2 x cheap periods with Octopus Cosy. Right now we have 50% of the ASHP in the cheap period and 50% of the usage during the 'normal' period. One frustration I do have, is that for the majority of the heating times, our flow rate is around 30degs which means it takes ages to warm up during cheap & normal rate periods...but oes eventually get there with a 'high' flow rate temp of low mid 30s. I am weighing up for 'winter' periods disabling Weather Comp, setting the flow temp at a flat 37 degrees (so still 'ok' efficiency wise) and using this to get more heat out of the cheap periods, and reduce our usage of non cheap periods. Even if we take a 20% hit on efficiency going from a weather comp'd 30 degs to a 37 degs flat temp.... then the 30% cheaper rate elec still means we are quids in, and have a quicker warm'd up house! Just wanted to test this logic with the team! Cheers,

Wonder if you could use porcelain tiles?? They come out of a kiln... Though IANAL

We did have mains gas as an option, and I'm only 70% sure ASHP was indeed the best short term solution (I don't think we will get the gov grant for our installation) . Long term I'm very confident it will be, as electric & gas prices are disconnected/swung as more renewables come online, but having watched it during a week of sub zero temps I accept there's more compromise then I was expecting. Hence always warning people to really REALLY be sure ASHP is the right thing to switch to, and to never rip out a working gas system 'because ashp is in the news and everyone is discussing it'.

I own a ASHP in a modern new build house and I'm happy enough with it... But your application makes no sense. Huge up front investment, more so borrowing the money, for a payback period you'll never see. Any sustainabilie benefits are lost binning a perfectly good gas boiler and radiators for a new toy. Also assuming your small garden (nevause new build?), where will it go? How will you route the pipes into your property? How will you route power cables to the outside unit? They are noiser then I imagined, which in a new build small house you will likely hear, as will your neighbours. Really really spend your money elsewhere, solar panels and a hot water pv booster for example!!

Not a dissimilar position to what I found myself in last week! Let the floor get too cold experimenting in the cold weather and there wasn't the warmth to enable the defrost cycles to run effectively vs getting raw warmth into the slab! Lots of energy for little true warm up of the house We only have a 60mm slab so can't coast as long through sub zero average temps.

Aa said, I've seen worse and you'd be amazed at what plumbers will do butchering their way through these, only to then hide it below some ply and tiles!! Sister joists, glued and screwed well and forget about it!

Found it! it's the MVHR, turned them both off at the mains and all looks to be be resolved after 14 hours. After several hours of research found someone on Facebook who had similar and discussed it bring an anti frost thing the MVHR was doing. Having looked at the MVHR manual (vent axia sentinel) it does say below 0 degrees it does activate frost protection. For now, I'm just happy to have found the culprit.

Could at lest expanding foam over the pipe? Do insulate the recirculation pipe at least!!

Another room.... Over the course of 24 hours later

So despite heating off from 4pm through to now... I'm still getting these odd bloody spikes!!! And they always seem to start around 1.30 am it seems...

Thanks Mark, I will do that! In the meantime I had a long chat with Joules (supplying & who spec'd it all) on the performance of the system & struggle we have in actually getting the house to warm up sufficiently & some odd temp drops we see. They have proposed that with us starting the heating across the FULL ''cool'' house at 3am during -3 degree temps, what is probably happening is the ASHP runs at full whack to pump heat into the house....and because -3 degrees it runs into defrost cycle reasonably quickly. However, due to a cool house & very low flow temps when the defrost cycle kicks in & the ASHP pulls the flow back/uses the UFH temps (which are every low) to defrost the defrost takes longer to run, before the system then restarts and heats the house. At this point the zones are now cold (because defrost cycle drawn back out what little heat) so the ASHP goes into full whack mode....and frosts up. It then reveres & what little heat it has put into the house....is pulled right back into a prolonged defrost period. We have a 50-60mm screed over a full 275sqm bungalow so lower retained heat capacity. We therefore end up in a vicious cycle, created by quite a 'cool' house in the first place. They have recommended we turn it off over night & run it for the course of the day tomorrow & weekend during the warmer periods of the day, to see if this is enough to break the cycle and get real warmth into the slab & house. There is a logic in this, however the really short & odd spikes are unusual all the same, and are possibly caused by the above behaviour!?!?!. They only appeared/appear during the really cold spots (and flatten out when the day warms up). Heatmiser possibly being very sensitive (which it is, I can detect when kids open their door in the morning based on the change in their room temp!!) could be picking this all up due to the 50mm screed acting quite quickly to the change in temps from defrost cycles? If a ''turned off'' ASHP freezes up/detects its frozen (or was frozen when the heating turned off)...... would it still kick in a defrost cycle?

For what its worth, the whole system has been performing pretty well & normally up until the temps dropped this week. Some of the kids bedrooms don't heat up as much as I would like, but they are small rooms, with very high ceilings & carpeted so not unexpected -vs- tiled rooms! Big kitchen has always heated up around 1 degree an hour for October/early November without any issue etc Checked out energy usage so far today and it looks to be around 36kWh for the day to sar, which for nearly 9.5 hours of a 12kw ASHP operation seems remarkably low! Also a flow temp of 32 degrees after a few hours of operation also seems too low....!?

No idea at all! i'm struggling to even imagine what it is. We have MVHR going, and do notice in the morning when some bedrooms are opened the temps really jump as the central corridor retains more heat then the rooms with big windows coming off of it. The fact it is shown in both the Master Bedroom & Kitchen...opposite ends of the house & different MVHR is even more perplexing.... Also shows up in kids bedrooms...

Thanks all, ill add some more details here: We have a large bungalow, lot of windows but good insulated. Ait tightness of 2.2, 160mm PIR in floor & ceiling, 150mm dri therm 32 full fill cavities. Every bit of insulation double checked during installation by myself. It isn't great by buildhub standards/passive, but it is well insulated vs your average new build. Samsung Gen6 12kw ASHP, supplying Joules spec UFH throughout with Heatmiser controls. We have c20 zones of UFH (as 6 bedrooms, 3 bathrooms, large kitchen & lounge with multiple loops etc). It is over zoned but it is all controlled together, controlled as all on & all off during cosy periods. This is why 16 degrees during night to keep all zones ''off'' then boosted to 21 degrees during the 2 x Cosy periods/an hour either side of them. Heating periods right now are 3 am to 8am and 11am to 4pm, with 1 hour DHW first thing & last thing within Cosy periods.... all on via 21 degree temp then all off via 16 degree set back. House holds the heat pretty well loosing 2 degrees over night with the -3 deg temps. Flow temperature right now is 32 degrees out of ASHP, supplying two manifolds. No blending valves on the manifolds, flow rates between 1 and 2L/min. All stats are next to sockets in each room, with UFH below carpets in most rooms. MVHR is on & used throughout. After the day today, this si what it looks like...again showing the heating on & hooting off periods....

To add to the above, we have a lot of zones throughout the house, but they are all being operated together....ie all open for 2 x 4-5 hour periods a day.

Checking how our UFH and ASHP performed with the recent cold snap, and our heatmiser app is showing some really odd behavior... Per attached pics. The tiled rooms are hit harder then those carpeted, I'd almost suggest closer to the manifold the bigger the drop. What is causing these large drops? Could it be defrost cycles? Anything I can do to soften this happening, as it is really slowing down the warming up of the house.

I did exactly the same, and have exactly the same loss. It still bugs me, massive insulation around the pipe, fastidiously applied... Nigh on bugger all difference! Grrr

Expanding foam around them?

100% insulate the hot circulation pipe at the very least, otherwise it's basically a radiator dumping valuable heat in a non valuable space!! Im also 90% sure it's in the building regs to do it as well....

We're due to submit ours in the next month or two, is this live now?

Our first winter in our new build, big bungalow is showing its down sides with the extra walls and floor drawing out heat. Lots of big windows reminding us of their presence as well. Im octopus cosy period, which was fine for the October to November month, but last couple of weeks and the week ahead I am adding extra time before/after the periods now. What is more efficient at hammering the power during Cosy periods... Starting the ashp 30mins before the cheap rate to enable the system to wake up and ramp up in time for cheap rate.... Or running the system 30mins after cosy period where the system is running at a steady rate?

We had sliding corner doors, and had about 40mm on both sides against the vertical steels. I was annoyed at the size, but quickly forgot about it! Now with plasterboard and external trims and render you'd never know! Accept what you've got, nobody is going to replace them to gain maybe 15mm. Top rule of self builds... Pick your battles, and know when you're not going to win! Move on.

Just a feature heatmiser offer!