Central heating

[Oldgreybeard]

Starting to cool down a little bit here, too. Hall temperature is down to 22.4°C this morning, after a couple of slightly cooler days. Heating is set to come on at 21°C, though, so it will probably be a few more days until it comes on for the first time since March.

[Mart]

I did set the boiler for two 20 mins burns (morning and evening), but it hasn;t done much yet. Most heating so far is from a 3.5kW A2A unit using PV. Currently on in the front room, set for 24C, and door wide open to heat through the house. Room gets hot (about 22C), but heat 'loss' to the rest of the house is excellent. But with E/W panels, spare PV will start to drop off rapidly now in Nov.

[Gareth J]

This winter will be interesting. Few more panels and a better heat storage system for excess wind/sun.

So far, the boiler has only fired twice and we've lit the woodburner 3x. Otherwise, all hot water and heating has been from diverted renewables ("lost" energy from bought in household electric uses aside). October hasn't really been a fair test though. It's been warm and windy. I know that there will be a point at which I have to convert the Rayburn from diverted renewables heat store, back to oil but the longer we can comfortably hold off, the better. You get quite used to going into the kitchen in the morning and using the temperature of the Rayburn as the world's most convoluted anemometer.

[Oldgreybeard]

Weather seems to have turned mild again. The bright sunshine we had in between the heavy downpours has given us enough solar gain to push the temperature in the hall up to 22.9°C, so it seems unlikely that we'll need heating for several days yet. Living in a passive house is great in terms of low energy consumption, but we find that it can easily get a bit too warm at this time of the year, from a combination of the low angle of the sun (makes it penetrate deeper into the house through the windows) and my reluctance to use the aircon when there isn't much excess PV generation. My wife's been on at me this afternoon to turn the bedroom aircon on again tonight, as she feels it's a bit too warm up there. So far I'm winning the battle by just convincing her that it's just her overheating, not the house. Not sure how long that will last before she twigs that it's not just hot flushes . . .

[Stig]

I finally gave in. It's only 16.5C in my living room so I've lit the pilot light and switched the heating on.

[nowty]

Just running on the A2A heatpump, lounge is very toasty.

[Oldgreybeard]

Not going to be long before our heating comes on, I think. Been very windy and wet here for the past day or two, and the house has dropped below 22° for the first time in weeks. It's currently 21.8°C in the hall, considerably cooler than it has been for a long time. Not been this cool in the house since I stopped routinely running the aircon to cool it down several weeks ago. Still not that cold outside, though, it's 13.2°C at the moment, so still pretty mild for November.

[SafetyThird]

Heating's been on for a couple of weeks now. We've had issues with the GSHP for the year since we installed it. Recently had a conversation with the director of the company that installed it and have now removed all the TADO valves from the radiators and replaced them with standard TRV's (which were in a box as they came with the rads from the original install). The system is running more stably and the house is more evenly heated.

Originally the idea was to have a Tado stat on each radiator and be able to set the rooms to whatever we wanted. However, talking to the director, this apparently messes with heat pump which is setup so that the rads in each room are sized to provide the needed heat output to keep each room the same and give the necessary flow. With each room able to close the radiator off, that changes the flow pressure and each room can call when it wants heat which messes with the timing that the pump runs for.

We've had multiple overpressure errors in the past with the pump eventually shutting down after 3 of them in a row. Since changing to the TRV's there's been none, the system runs a bit more quietly and the heating does seem very stable. So, apparently, in this case, simple seems to be better. We just have a single Tado, wireless stat in the hallway and that can automatically turn the system off when the front or back door is left open but otherwise the system seems to be running very well now.

We have a big enough battery pack that for most of the time the pump runs off it without grid input unless it really needs to crank up or we're cooking in the evening as well. Be interesting to see how much peak rate power we use over the winter and may add an additional inverter next year to give us 7.2kw of battery output instead of the current 3.6kw if it looks like it would be worthwhile.

We've had the woodburners lit on cold, wet evenings more for the joy of it but it all adds to the heating mix.

[Oldgreybeard]

Had a similar issue when I first commissioned our heat pump, although it's running UFH. I'd fitted electrically controlled, self-balancing valves to each zone and when the heat pump fired up it would often throw an over-pressure error, because the valves take a minute or two to fully open. The fix for me was to fit a low loss header to the heat pump, so there's a low resistance bypass path if the valves are closed. Since doing this I've not had any problems at all with it. If the valves close then the flow just short circuits across the LLH.

[MrPablo]

Yes, it seems micro zoning and heat pumps don't tend to play well together.
I watched a Heat Geek video a while back that covered this in some additional detail.

There's also a school of thought relating to micro zoning and combi boilers not always working as efficiently either. I'm experimenting with less extreme set-back temperatures and seeing what the results are.
The Drayton Wiser system I'm using has been reset and is relearning the house, hopefully it'll work well.

For extra information, I use an OpenTherm gateway between the boiler and control unit to monitor what's going on.
I also had to use this to override the Viessmann boiler setting max CH flow to 80 degrees when running in OpenTherm mode - it seems they have a buggy implementation.

Curious to see what control and monitoring systems people are using in this forum, especially with heat pumps.