Whats the problem?

rredbob

I have a system boiler (34kW) which is attempting to feed 18 radiators (split into two zones) in a 5 bedroom house, i am struggling with only heating 12/13 radiators, they are not getting very hot either and boiler ramps up to max heat and cuts out and then lights up again after 15/20 secs. (Boiler is a Sime Murrelle HE35) Eventually settles down but boiler heat symbols never goes above 1 or 2 marks.

I have been told to fit a low loss header manifold and additional pumps, will this sort out my problems?

Also it sounds expensive, but any advice on this matter would be appreciated.

The pipe diameters to the radiators are 10mm (not helping matters i think).

System pipe work and rads are clean, with very little sludge or iron matter.

Any advice would be appreciated and quickly please, its getting cold!!

I have also noticed recently that when heating the hot water storage tank, which is very close to the boiler the boiler still ramps up and goes into the re-lighting sequence as mentioned previously, the boiler heats the water but I think something is not correct.

Could it be the flow (or not) of a pump which is not performing correctly?

The boiler is 3 years old.

lchmb

have you

alway's had this problem since install? Is it possible to get some pic's of the boiler and piping in the boiler room?

rredbob

Reply

Yes I have always had this problem

Steamhead

Also

where are you located? That brand of boiler isn't one I recognize as being sold in the States, where most of us are located. 

Jamie Hall

The boiler...

may be unfamiliar (it is!) but the physics doesn't change -- thank goodness.  At the risk of wandering too far out on a limb, it sounds very much to me as though your system isn't able to circulate enough water through the boiler to take its heat away -- and as a direct consequence it can't circulate enough water through your radiation to warm things up.



Fine so far.  However, without knowing a good bit more about the pump(s) involved, I can't go much beyond that. 



You might be able to reduce the head loss by some very clever manifolding and get more flow -- but how much more flow that would produce is dependent on the characteristic head vs. flow curve of the pump.  Unless it's a pretty flat curve that may not work.  And it will be tricky to get even flow through the system.



Another possibility might be to increase the flow rate by installing a pump capable of handling a higher head loss (thus creating a higher flow) -- but you may have problems with that with regard to the maximum pressure the system can handle.



There are a variety of methods involving the low loss header manifold you have mentioned, with additional pumps to handle the various zones.  They work.