Was boiler guy talking rubbish?

Max_Admin

I heard or read somewhere that at least 1 rad has to be on full and you can't have thermostatics on all

Pincher

Before TRVs, the radiators allowed the water to flow freely, unless you deliberately closed the valves on the radiators. If you don't want any heating, you wouldn't go round shutting off all the radiators, you set the timer to off.


With the TRV, it shuts off the radiator it controls when the room temperature has reached the set point, so there is no flow. If all the radiators are closed, the hot water does not flow, and guess what:


1. The pumps keeps pumping, overheats and dies.


Well, maybe forty years ago, now there is a by-pass valve.


2. The boiler keeps heating the static water.


To prevent this kind of stuff, they have overheat temperature sensors, temperature and pressure relief valves, etc. , because the engineers know the user just can't help fiddling with their knobs.


30 years ago, I had a blow-out from a gas water heater, the flow sensor must have failed, and the boiler kept heating after the hot tap was turned off. The weakest point was a solder joint in the hot water pipe: BANG.


So, it's perfectly OK to shut off all your radiators, because they put in safety features: until they stop working, and you don't know about it.


So, always leave one radiator flowing, usually the towel radiator.

JC1440

Thanks, all.

St999: had them all on earlier for twenty minutes and it stayed on.

Adonis: I don't believe so. One of the rads just has a thing to twist clockwise or anticlockwise to alter the level of heat. The other three has a thing you move up and down to select between one to five, that being the level of heat you want.

Botmission: I hear ye, but it doesn't seem so much like a fault. I mean, it doesn't do it everytime.

Pincher: I always have at least one rad on. It's not often it's just the one I have on, but sometimes I just want heat to the one room.

Should I just get the people that fitted it to come back? Surely such an expensive boiler shouldn't require ongoing threads on this website?

JC1440

adonis wrote: »

I have the same boiler, when the room stat calls for heat the boiler fires up and the temperature reading on it builds up to 75 degrees in economy mode.

Then you can hear the boiler slow down as it keeps the radiators at 75 degrees, it doesn't go to standby.

When the room required temperature is reached the boiler flame goes out and the boiler shuts off after a few minutes.

You don't have thermostatic valves on all the rads do you?

I mean, is the most simple thing to ask, if I want to run just one radiator, on a medium setting and the boiler set to ''energy efficient'' Should I be able to do that for more than eight minutes without the flame going off? And should I be able to run three radiators, again on a medium setting, and the boiler on ''efficient'', for more than twenty minutes without it cutting out? If the answer to both is ''yes'', then I need to get these people back in.

macman

If the system can't raise the room temp to, say, 20C without cutting out, there is clearly something amiss. Setting the room 'stat to 30C is pointless, because that temp is way beyond what you'll want to achieve in normal use (typical living area temp is maybe 18C to 22C).
It's not whether the boiler is 'cutting out' or not that matters, it's whether the zone is up to the set temp or not when it does so. If the programmer is still calling for heat and the boiler won't fire in response, something is wrong.

ollski

If you only have 4 radiators the boiler will still be producing too much heat even when it modulates down to minimum so it will need to shut down and pump the excess heat round until the rads use it up. Then it will refire and repeat.

JC1440

macman

If you mean is it cutting out before it reaches the temp on the thermostat then yes, it cuts out way before. That's why I set it to 30, just so it wouldn't ever cut out. It cuts out at 13.

I just ran the one boiler. Flame stayed on for about eight minutes, went to standby for a few minutes, then came back on for another eight minutes, standby for a few minutes and back on. Is that because like ollski says, it's just releasing excess heat? When I have three rads on it appears to be staying on the entire time now, although the longest I've had it on is twenty minutes, with it getting a bit warmer now. Will leave it on for the full thirty I usually do later and see if it stays on. Also, water heat seems to be normal, doesn't appear to cut out when I'm having a shower.

lstar337

JC1440 wrote: »

I just ran the one boiler. Flame stayed on for about eight minutes, went to standby for a few minutes, then came back on for another eight minutes, standby for a few minutes and back on. Is that because like ollski says, it's just releasing excess heat? When I have three rads on it appears to be staying on the entire time now, although the longest I've had it on is twenty minutes, with it getting a bit warmer now. Will leave it on for the full thirty I usually do later and see if it stays on. Also, water heat seems to be normal, doesn't appear to cut out when I'm having a shower.

Exactly what Ollski says.

Mine operates the same.

You simply don't have enough rads on for it to run flat out continuously. If you watch/listen you will find it is still running the pump. It is cycling the water around until the temp reduces it enough to fire the burner again.

If you are only going to run one rad, you are going to have to give it time!

lstar337

Why not run all the rads?

If you just heat one rad/room, the moment you open the door all the heat escapes. Better to run more I would think. The boiler will be happier not cycling on/off all the time and the house will be warm throughout.

Lum

Also the radiator(s) in the same room as the thermostat need to be set to maximum, otherwise the two systems will end up fighting each other and possibly waste energy.