Raising boiler temperature

[ljmountain]

I have a regular condensing boiler (Greenstar 12Ri), open vented system with HW tank. I am trying to increase the temperature of the water, current water temp is 60 deg.

I've turned up the thermostat on the boiler to maximum (instructions say this should be 82 deg. I've also turned the HW tank thermostat to 70 deg.

I've run some tests and cannot get the water any hotter than 60 deg.
When I turned the themo up on the HW tank, I heard it click and watched the actuator valve open. The boiler is the first device to turn off (green light goes off), this leaves the pump and actuator valve open.

I would have expected the boiler to be the last device to turn off (i.e. after the actuator has closed because the HW thermostat has told it to). My theory is that something is wrong with the boiler themostat but will be the first to say that I don't fully understand how the whole system works.

Does anyone have any advice or suggestions.

Why changing temp? Diagnosing problems with Trevi Boost Shower.

Thanks James

 

[moggridgeplumbing]

The answer may not be either of the thermostats but your pump, or at worse a resriction in the flow from your boiler around the hot water cylinder and back to your boiler.

Check to see if when the boiler fires up that the pump is running. If the boiler cuts out fairly quickly and overheats that can also indicate a possible pump problem. Is the central heating side working ok? or are the ground floor rads more luke warm. If so pump is the problem.

When the pump is off try turning the speed up, for example from 2 to 3, and see if that makes any difference. If yes change your pump. If no get a heating engineer to test it.

 

[oph]

...........
Why changing temp? Diagnosing problems with Trevi Boost Shower..........

Whats the problem with the shower then

 

[dogfonos]

Circulating pump on my neighbours system broke and although their radiators were only slightly warm, the boiler kept shutting down when you'd have expected it to keep heating. Turned out to be a knackered pump although not obvious to me at the time as the pump was still running and not making nasty noises.

Because you have an open vented system, take a look at the expansion pipe that feeds back into the TOP of the expansion tank (it does on my and my neighbours systems anyway) - if it's hot due to ejected boiling water from the boiler's heat exchanger (as it was in my neighbours case), then moggridgeplumbing is probably correct about the dodgy pump or (partial) blockage.

 

[ljmountain]

Thanks for replies.
- All radiators are hot upstairs and down.
- Pump is running when boiler fires up and stay running
- so looks like heating engineer

 

[kittedup]

Hold the phone, how long ago did you increase the stat on the HW cylinder?

If the water is already stored at 60 and you have upped the temp recently the boiler won't be disappating it's heat very quickly and will short cycle as you have seen.

I'd wait until tomorrow before calling anyone in.

Ted