Having to run the boiler at high setting 6

[mickecob]

I have a heat only 's' plan system with a Bosch Worcester greenstar 24i on a twin coil Oso solarcyl 200 lt. The boiler has to run at max to heat the water but this means the rads are too hot and I would like to lower the boiler stat.

I realise the hot water temperature will only obtain the the same temp as the rad side. Also if the water is fairly hot but needs boosting and the heating switches in from cold with both calling the hot water tank becomes a heat store and the water temperature drops.

My question is can this situation be better controlled electrically allowing me to run the rads at a slightly lower temp and the hot water maintained at a higher temp with out the heat being syphoned off.

Cheers

Mick-e

 

[lame plumber]

cyl stat needs setting to 55 and then water will be hot enough and rads cool enough simples.

 

[SimonG]

Shouldn't be syphoning heat from cylinder though.

 

[Best]

Why do you sat the boiler has to run at max to heat the cylinder?
Boiler should be fast enough to heat the water even if at a lower heat setting.
Your cylinder stat should be set at 65 degrees. The radiators should have any circuit controls (room stats etc) set to proper limits - 17 degrees for bedrooms, approx 20 hall, 24 perhaps living rooms. Radiator TRVs should be all set to proper lower settings. Rads to touch will still reach whatever boiler is set to.
Use if possible your boiler on hot water seperately. That way it will heat faster and will not be initially robbed. Rad circuits will work better when the hot cyinder is removed from demand.
Have your cylinder checked to see if any reduced flow valve is fitted

 

[Stanios]

Look under your boiler leftmost 22mm pipe (flow) does that tee off near boiler into the rightmost 22mm copper pipe (return) with a valve fitted on this connection? If it does, fire up your boiler and put one hand on the return pipe just after the valve and other hand just before that valve. One side should stay relatively cold, if both get really hot in under 2 minutes see if you can turn the valve down try again. If it still letting hot water through get a plumber in to remove it, that boiler has an internal bypass doesnt need an external one (yet many plumbers still fit one anyway) This causes your boiler to basically circulate around itself

 

[jtsplumbing]

What other controls do you have ? Stats on each radiator, room stat, sounds like you have a faulty stat on cylinder or faulty valve.

 

[mickecob]

Thanks for the replies guys, I have hall stat + TRV's with stat set at 60/65.

Could this be a poss prob I have 22 mm pipe to and from hot water tank with 22 mm coil, there is no flow control valve does it need one, is it likely to fool the boiler into backing off not sure if this would have an effect.

System fitted with an auto bypass to secondary water tank coil, doesn't operate until either water or rads stop calling. Was going to have solar water heater to this coil but been advised its a pain to maintain.

PV solar and an immersun on the immersion heater seems a better option instead.

Thanks again

Mick-e

 

[jtsplumbing]

Must have a MV on cylinder, to control heat, you have an unvented cylinder, if you have no valves controlling it you need this sorted asap Some photos would help

 

[Stanios]

Without motorised valve and cylinder stat you can't really heat any cylinder properly, its bizarre not to have that since most cylinders come with those components and as jts mentioned they are mandatory on unvented.

 

[mickecob]

Sorry 2 single port [S plan ] controlled by stats and yes unvented cyl. with reducer, relief and over pressure valve with drain. + expansion vessel.

When Best suggested it was not set up as good as it could be it made me think balancing rads, does the heating coil need balancing.

When I mentioned no flow control I meant as in a lock shield on a rad. Once the MV opened would the 22 mm pipe short circuit the
heating circuit returning very hot water to the boiler, almost like a bypass, [boiler is next to the tank] if this is occurring how would it affect this type of boiler.

Will get some pics together if this will help.

Cheers

Mick-e

 

[Neil K]

Always good practice to have a 22mm gate (or lockshield) valve fitted on the Hw primary return pipe on the cylinder to stop the Hw robbing the heating. If it's all piped up correctly then should have no affect on the boiler. On unvented you could get away with lowering your cylinder stat to 55 MAX.

 

[gmartine]

cyl stat needs setting to 55 and then water will be hot enough and rads cool enough simples.

Why do you sat the boiler has to run at max to heat the cylinder?
Boiler should be fast enough to heat the water even if at a lower heat setting.
Your cylinder stat should be set at 65 degrees.

What other controls do you have ? Stats on each radiator, room stat, sounds like you have a faulty stat on cylinder or faulty valve.

Check the cylinder stat(s).

 

[Stanios]

Your cylinder should heat up in 30 mins from cold to hot if boiler is doing just the cyl. Rads are meant to get HOT that's how they work if your room gets uncomfortably hot turn trv down to 2. If your house gets too warm your roomstat needs to be in a room/area where the adjacent rad has NO trv and isnt shut off otherwise. Make sure your roomstat actually works and is roughly accurate temperature wise.

 

[Neil K]

As above- heating is about COMFORT. Room stat and trvs should also be correctly set up and doing their job.