Combi boiler flow hot return cold

[joetheghost]

Half my rads are working but they all have a cold return ,as does the boiler.If I use a desludger will this do any good as the chemical will not be able to circulate.I have tried flushing out the pipes only shutting down the rads but this has no effect.The boiler runs for about 20 secs at a time before clicking off

 

[SimonJohns]

You have a lack of circulation. Try just one rad. Trv fully open and lockshield fully open.

Report back with results. This could get complicated

 

[arran197]

Sounds like you have a blockage. It could be on the return valve to the boiler. Some have a filter. Come across a couple of Baxi Magaflo's with a blocked return filter, exactly the same fault as you are describing.

 

[LF Heating]

Yeah sounds like circulation problem which could be caused by blockage, faulty pump, insuficient water in system, scaled heat exchanger, sludge, blocked magnetic filter or various other problems. Try powerflushing using pump head adaptor but also ensure boiler is full of water, any air vent are working and vented. Cause of action depends on sytem type. More info required. Cheers liam

 

[LF Heating]

Sorry didnt see you said combi. Powerflush from pump( this will also test pump is working 100% and check aav. Sometimes pump looks like its running but is easilly stoped or just slow) good luck. Also may shift blockage.

 

[joetheghost]

You have a lack of circulation. Try just one rad. Trv fully open and lockshield fully open.

Report back with results. This could get complicated

Hi
Thanks for your comments, B Gas have been and checked the system and tell me there is a blockage,pump is working,boiler reaching required temperature.His solution is power cleanse ,I simply can't afford that.
I disconnected flow and return pipes and connected one end to the filling loop and the other pipe to the bath with a hose and ran for 2 hours and while some sediment came out ,it wasn't enough to cause a blockage.I then repeated this operation in reverse i.e conection to the return pipe and connecting the flow to the bath and repeated the operation,in both direction the flow seemed uninterupted.Previously to this about a week before I had a strong tomato soup colour coming from the hot tap,the cold tap and the wc,these are fed through a watersoftener.B Gas were called out after it had cleared and said ,after speaking to Saunier Duval technical dept ,the problem had to be from outside source,I said the mains was clear and that would also have been affected but it wasn't.They shook their heads at that.
I also told them the filling loop took about 2 hours to replace the pressure lost ,after bleeding the rads ,this suggested to me,a blockage in the boiler but they didn't agree.I also theorised that some pressure in the boiler must have overcome the filling loop valve(it wasn't non return as it should be) and flowed back into the hot tap cold tap and wc ,but they were adamant there was no switching parts that would have been able to have caused that.I didn't seem to be able to get past their claim for power cleanse or new boiler.They fitted a Spiroclens filter about 6 months ago which on emptying had almost nothing in it to cause a blockage,it seemed a complete waste of money £275 for a filter that didn't filter.Unfortunately some of my rads have O rings that leak through the flat head screw adjuster,so these won't allow some rads to be isolated.Hope this hasn't been too long winded for you

 

[kay-jay]

basically mate you were on the right track, connect your hoses up again preferably to rad valves after removing a small downstairs rad , close flow and return valves off on boiler, turn all rads off apart from one, flush with cold mains water if it doesnt run through reverse flow and try again. repeat for each rad one at a time. the aim is to achieve a flow into the bath or better still a grid from each rad, if this works then your heating should be ok, if it can't be achieved then whichever rad doesnt flow may need changing and/or a bit of pipework, only other alternative is powerflush - don't get from bg though!!! get a local independent in from 250 quid depending on location - much cheaper than bg.

 

[joetheghost]

basically mate you were on the right track, connect your hoses up again preferably to rad valves after removing a small downstairs rad , close flow and return valves off on boiler, turn all rads off apart from one, flush with cold mains water if it doesnt run through reverse flow and try again. repeat for each rad one at a time. the aim is to achieve a flow into the bath or better still a grid from each rad, if this works then your heating should be ok, if it can't be achieved then whichever rad doesnt flow may need changing and/or a bit of pipework, only other alternative is powerflush - don't get from bg though!!! get a local independent in from 250 quid depending on location - much cheaper than bg.

Hi
Thanks for the info,as it's early morning ,too soon to follow your recommendation,can you explain how ,if the flow and return are apparenly clear(this is in 22mm or 28mm pipe) would this affect the 15mm supply to the rads.I can understand one or two rads being blocked,but surely they would simply be bypassed and the circuit continue uninterupted.The rads that do warm up all have cold returns

 

[joetheghost]

basically mate you were on the right track, connect your hoses up again preferably to rad valves after removing a small downstairs rad , close flow and return valves off on boiler, turn all rads off apart from one, flush with cold mains water if it doesnt run through reverse flow and try again. repeat for each rad one at a time. the aim is to achieve a flow into the bath or better still a grid from each rad, if this works then your heating should be ok, if it can't be achieved then whichever rad doesnt flow may need changing and/or a bit of pipework, only other alternative is powerflush - don't get from bg though!!! get a local independent in from 250 quid depending on location - much cheaper than bg.

Just remembered,should have added this in my last reply a few mins ago.When I removed about 3 ltrs or more in order to add some chemical to keep system clean,I noticed the needle pressure didn't go down as I thought it should with that amount being taken out.

 

[vectra65]

pressure gauge pipe blocked sounds to me pump blocked up also

 

[arran197]

Sounds like the boiler has a blockage. Check with the manufacturer to see if the return has a filter on it and if it does take it out and clean it. I'd make sure you get some good cleaner through the system too, sentinel jet flow is meant to be good.

 

[Unregistered]

Any resolution to your problem? I have exactly the same problem!

 

[Rickster123]

Any resolution to your problem? I have exactly the same problem!

Please register and start a new thread. Thank you.