Central heating C Plan miss behaving but can't work out what is going on.

[ericmark]

Oil boiler is cycling on/off/on and hot water returns to boiler before it turns off, two pumps, two motorised valves micro bore main house 15 mm flat, flat works fine, main house hit and miss.

So tried each radiator non have really hot water on return pipes, radiators do get hot some times, but seems hit and miss, all TRV bases change when I moved in 4 years ago, all heads except toilet shower room are electronic all software say batteries OK, three makes of heads, Energenie, Kasa, and eQ-3 latter bluetooth version, main wall thermostat is Nest Gen 3, which is not turning off, so living room now Energenie 17ºC heating to 22ºC radiator cold, Kasa 17.5ºC heating to 23ºC radiator cold but some times the radiators do warm up, tried bleeding no air found, when flat motorised valve opens the main house seems to get warmer, I hear the pipes warming and cooling so water is getting through some where, when we moved in no motorised valves and which ever pump ran the water would flow in reverse through the other pump which is why valves were added.

If it did not work, could likely work out fault, but it works some times, and the old smashed TRV head sitting on mantle place is showing 19ºC so living room is heating up, but intermittent.

Age concern is sending some one around a week tomorrow, maybe he can help, I tried balancing radiators when I first moved in, just made it worse, so living room lock shield valves are now wide open. top floor bathroom is therm-syphon as is DHW with it seems no way to regulate flow.

I have not found a by-pass valve, but the flat use to be a garage under the main house, and the plaster board now hides pipe work and wiring. I really don't want to rip plaster board off the walls, the pumps are on the return so can't see how a by-pass valve would work.

At the moment the pipe to lock shield valve in living room is too hot to touch, Energenie TRV side just taken the chill off pipe, radiator just the chill taken off it. When the Energenie TRV's work you can hear them, and I have not heard them work except at 12 midday Saturday when set to exercise.

As said if it did not work full stop I am sure I could find out why, but this intermittent operation is driving me crazy. As I have been writing this the living room radiator has been getting ever so slightly warmer. But pulling my hair out trying to work out what is wrong.

 

[ericmark]

Two hours latter, nothing really changed, and now one radiator one and just about touch, and the other half has warmed up, and nothing has really changed. And this is my problem. All showing as it should but some times rooms get cold and radiators cold even when all showing as running. The old TRV head is sitting on the mantel piece and is showing now so room has warmed up as it should now, the showing of 21ºC, 17ºC, and 19.5ºC for same room is normal, it is heights of TRV heads and position, would not normally set to 30ºC but wanted to be sure the TRV was not the problem, over night heating will be off and tomorrow starts over over again, having no idea if room will heat up or not. Any ideas welcome.

 

[fixitflav]

Two hours latter, nothing really changed, and now one radiator one and just about touch, and the other half has warmed up, and nothing has really changed. And this is my problem. View attachment 328574View attachment 328575View attachment 328578 All showing as it should but some times rooms get cold and radiators cold even when all showing as running. The old TRV head is sitting on the mantel piece and is showing View attachment 328579now so room has warmed up as it should now, the showing of 21ºC, 17ºC, and 19.5ºC for same room is normal, it is heights of TRV heads and position, would not normally set to 30ºC but wanted to be sure the TRV was not the problem, over night heating will be off and tomorrow starts over over again, having no idea if room will heat up or not. Any ideas welcome.

C-plan has gravity HW, with a motorised valve, pumped CH. Is that what you have? What do the 2 pumps do?

 

[ericmark]

Yes gravity hot water, I called it therm syphon, but same thing, the one boiler heats both the flat and the house, and clearly the idea was that having a pump for house, and pump for flat would allow selecting between the two, this did not work, as switching a pump off resulted in flow reversing not stopping. So two motorised valves added to stop the reverse flow.

This does work, and we can now turn the flat off. In real terms set down to around 10ºC and the flat when activated works A1, but the main house is hit and miss, living room radiators are at moment hot, dinning table side is hotter than one TV side, but in the main heats the room, but then we will realise it is cold, and find radiators cold, and on checking find the radiators cold, but all three thermostats are calling for heat. And I am darned if I can find out why.

I have a suspicion that some thing is allowing hot water to return to boiler, so boiler closes down on over heat, but can't find out what, and next time I check, find it working as it should again.

So I don't expect anyone can remotely work out what is wrong, but they may have ideas of what to test. This morning I set both living room TRV's to 28ºC to ensure they are open.

and the main Nest in hall . Oh I am wondering if the Nest? On first looking saw then went to orange, so maybe Nest Gen 3 is the problem, had problems with Nest before due to EE mast being damaged and it thought I was not home, but walking past the thermostat would turn it on, so every time we walked past it was running, but would then turn off.

So I only get history on the next day, so I have no idea how long it has been running today until tomorrow. So there is a host of settings Sunblock (Off), Leaf (Ready), Auto Schedule (off), Time to temp (Ready), True Radiant (off), Eco Temperatures (Off).

So could the Nest be cause of my problems?

 

[fixitflav]

So could the Nest be cause of my problems?

Sorry, I don't know the first thing about Nest and similar. But it doesn't half look complicated! Isn't it possible to bypass it or switch it off, and just run the boiler from the roomstat?

 

[ericmark]

I have been considering fitting a second thermostat in parallel for the main house for some time. I delayed because I had seen these temperature sensors, but it said

The Nest Temperature Sensor works with the following thermostats:

• Nest Learning Thermostat, 3rd generation
• Nest Thermostat E

For the following countries:

• United States
• Canada
• Mexico

I hoped it would be released for the UK, and I was well aware Nest USA is not the same as Nest UK. But now I think time to give up waiting and fit a second thermostat in parallel, age UK are sending an adviser next week so I will wait to see what he says, but it seems likely I will fit a second thermostat in parallel.

 

[fixitflav]

age UK are sending an adviser next week

I didn't know age UK had CH experts, but you live and learn

 

[ericmark]

Phone call out of the blue, I get my nails cut, so on their list, may be down to this area having no mains gas? I do not expect they will help that much, but worth a try. The amount of time boiler running seems too short, schedule starts at 8 am, and each 5 hours it raises 0.5ºC until ¼ past midnight when it drops again, and this means it does not over shoot, and we like it a little cooler at night. But the time it has run for does not seem long enough, trying to work out why. Nest records when thermostat asks for heat not when boiler is running, so 12½ hours does not mean boiler ran that long.

 

[Terrywookfit]

Is there a relay to allow the boiler and pumps to run independently.

 

[ericmark]

Yes, should really be two, but flat never run without house.

 

[Terrywookfit]

Are both pumps running and M/V s open when there is a demand?

 

[ericmark]

Yes I have sat down in the flat, hand on pump so can feel it start, and both pumps work and both valves work, if it did not work it would be easy, every time I think enough is enough I am going to sort it, I can find no fault. The circulation does seem slow, but having seen it work when pump not running when I first moved in, it heats up too fast for a pump failure.

It has never been A1, when I moved in to put it mildly it was a mess, to get CH in main house, I had to switch on boiler with programmer upstairs, then go down stairs into flat and plug in the pump, powered from 3 FCU's and a socket from two independent distribution units, it clearly needed some work doing, and more than simple repair, as there were only two cores up to down stairs and colours turned from red, yellow, blue to brown, black, grey some where in the run, so seemed prudent not to use for low voltage, which is one reason for selecting Nest as the link thermostat to heat link is extra low voltage.

This is the as built now, I know there is a relay missing, really there should be two, it is an 8 pin valve base relay and there is space in the box to fit the second, but it should not matter as house used without flat, but never use flat without house. I had expected the plumber who fitted the motorised valves to go down to one pump, but for some reason he didn't.

There are 4 rooms in the flat, these have mechanical TRV heads, and a mechanical thermostat in the kitchen, works well, but flat not really used.

The main house 9 heated areas, the utility room not heated, the upper bathroom radiator thermo syphon, as is DHW, 4 upstairs rooms have 4 eQ-3 bluetooth TRV heads, also one in kitchen, hall, dinning room, and one living room TRV are Energenie the odd one in living room is the Kasa (TP-link) as one Energenie killed by carpet fitters. And don't like Energenie as you can't manually alter, have to use the PC.
I think the problem lies behind the plaster board in the flat, I tried to trace pipes, I got this far but you can see the unknown pipe, I could not trace where it went. I tried to balance the lock shield valves as done in last house, last house I would watch the computer read out, if target was higher than current open a little, if target was lower than current close a little, but one oil boiler does not modulated so turns on/off all the time, and the rooms never got warm, so opened most of them up again.

I do wonder if there is some by pass valve hidden behind the plaster board, as can't find out why hot water returning with no radiator hot. Could understand if all going through one radiator, but the micro bore seems to ensure all radiators get their fair share.

It was working of sorts until wife got two kittens, who will scratch at carpet if door closed, so doors not now fully closed, and this has tipped the balance, and we can't now get living room hot enough.

Boiler is cycling on/off, so not simply boiler not big enough. And also unused rooms we turn the TRV down, and only heat bedroom in evening and night, etc. Never have got the kitchen hot, although radiator get hot, blamed on unheated utility room with window open for tumble drier, but now have a heat pump drier so window closed, and kitchen still cold.