Gas: boiler off but one rad heats up

Hmm_Messiah

my mum has natural gas ch.

wbeing summer the switches/timers are all off, and boiler lights up only when the hot tap is run.

However she noticed two of the radiators get warm, we thought she was exagerrating, and manye just from sunlight shining in, but the other day a bedroom radiator was fully heated .

How is this possible ? (I don't understand ANYTHING to do with boilers, or how its heating only ONE radiator though the others are turned on, only OFF at the boiler unit)

Lex Luthor

does she manually close off the valves for each radiator in the summer?
If so, has she made sure this rad that heats up has definately been closed off?

Sounds like the valve isn't closing properly.

Hmm_Messiah

she doesnt turn off the individual rads, she is not well and would be furstrated trying to rem etc, the boiler is set to "water" only
thats what i don't get, how is a radiator heating, and why only one in the circuit ?

Lex Luthor

sounds like this rad has not been isolated in the plumbing.

is this the first time it's happened?

Hmm_Messiah

nope, i think she mentioned a few times last yr (system is 3yrs old)
we kinda didnt pay much attention to her
she lives alone

so any idea is this a big job?
and/or should we expect the guy who installed it to fix ?

as it is the pressure CONSTANTLY drops and i've had to use realise valve to bring it back up to 3 (bar??) etc. I understood the only way this would be happening if a leak somewhere but he never came back to check it, i wondered could i contact Bord Gais about it, surely he has some responsibilities if listed as an installer with them

thanks for the help,

davidoco

3 bar sounds high but I can't suggest what you set it at.

My guess is that the rads have been there longer than the gas boiler and the existing system had one rad in front of the zone valve (zone valve stops water going out on a circuit) which now acts a heat leak. There is no need for that with modern boilers (sealed or not) but cagey plumbers 20 years ago putting in oil or gas boilers would have been afraid that thermostats would go and keep the boiler running even though no heat was being called.

Is it a combi boiler, ie do you have a hot water tank or does the boiler run only when you turn on the hot tap and stop just after you turn it off?

Hmm_Messiah

hiya

no boiler , runs when water on, then shuts off

and the radiators went in with the system, house had no CH previously

we used move the pressure thingy to 3 becuase otherwise would drop too low before we saw mum again, though not sure how that is presentl when heating not being used

davidoco

New system, ok that's interesting.

FYI - remember that the mains pressure water going to the hot taps never mixes with any other water especially the heating system, it just passes though the boiler and gets heated as it passes a heat exchanger.

If your sure that the heating control is off then there may be a heat leak to the part of the boiler that serves the heating which should be looked into asap or more likely a fault in the electronics of the boiler which is firing up up the heating circuit. Since the pump for the heating may not be running it is heating the nearest or highest rad by a thing called thermosyphon? where hot water rises to the highest point and moves itself slowly like would have happened in old solid fuel systems.

It would be something that a service should be able to identify and solve. It's always interesting to get somebody out to service a system that they didn't instal as they may have interesting comments to make on what was installed.

PS the other day I had a Bord Gais approved guy out to service my gas boiler. The set charge is 90 euro for the first hour + parts. He was with me for 1hr and 6 minutues and he charged me 20 euro extra for those 6 minutes!

Hmm_Messiah

my mum wondered about that service charge too!!
ok I'll re read your post and try get my head around it
i think basically needs to be serviced, and best to get different guy to service it if want and faults actually mentioned .

tapest

Hmm_Messiah wrote:

my mum wondered about that service charge too!!
ok I'll re read your post and try get my head around it
i think basically needs to be serviced, and best to get different guy to service it if want and faults actually mentioned .

Hi
This may / may not be relevant. Sister had Gas C/H installed from scratch...no conversion. The system is a "sealed" system, no header tank, uses an expansion devise instead like a metal football, containing a bladder surrounded by inert gas. She has the ability to turn off rads and/or hot water manually using 2 gate valves. In the event of both valves turned off together accidently and the boiler left on, the system should still be safe with gas boiler shutting down on temp control and if this failed the pressure relief valve should open. EVEN with these 2 safety devices, a single radiator was deliberately plumbed in such a way so that if boiler is on it heats. If the user decided to turn off the lockshield valves on the sides of this one rad, they installed a rad by-pass ( the two pipes from this rad are joined together under the floor, with a gate valve partially open on this line, with the handle removed. Plumber called this "by-pass limiter".
As I say this may not apply to your system, but the point I;m trying to make is that it may be designed that way with over the top safety, if there is such a thing,
hopes this helps
regards
t

PS working pressure is under 2 bar, red warning indicator set to 3.25 bar
t

davidoco

Hmm_Messiah - any update on what was causing the heat leak