Issue with central heating circulation

[Jamie Arnold]

Hi, I have an issue with radiators not getting hot. The boiler runs fine, the pumps only a couple years old and runs ok but there appears to be no proper circulation. The flow pipes get hot but the return stays cold so I know it's an issue with circulation system, I've used a system cleaner which didn't help, it was a gravity fed system so turned into sealed system with 1bar pressure which also didn't help. Pipework from the boiler is 28mm, by the pump is 22mm and feed to radiators are 15mm. Short of having the system power flushed has anyone else got any ideas?

Thanks

 

[rpm]

Central Heating Forum

There is a very good post in here about how to balance the system, good cheap place to start.

 

[ShaunCorbs]

Central Heating Forum

There is a very good post in here about how to balance the system, good cheap place to start.

Croppie's Balancing Thread.

 

[rpm]

Croppie's Balancing Thread.

Yes Shaun I know what it is called thank you very much !!!!!!!!!!!!!!!!

 

[ShaunCorbs]

Yes Shaun I know what it is called thank you very much !!!!!!!!!!!!!!!!

Yours doesn't link anywhere other than the ch part ?????

 

[rpm]

Read it again then and find the word balance in my post. I`m sure the OP is capable of operating their keyboard to find the desired intel for themselves.

 

[Old Account]

But is that really a balancing issue if the return pipe doesn't get hot at all? There must be circulation issue?!!??!!?

 

[Last Plumber]

Might be a silly question but here goes!

All rad valves are open are they?

 

[Jamie Arnold]

Yeah all rad valves are open and 2x rads were changed to new ones, I've tried balancing rads but still no joy. I know it's an issue with circulation but trying to figure out what it is and how to sort, I'm guessing a blockage of some sort. I've used a system cleaner that did nothing, each time drained the system water cones out clear but with it being an old system I didn't really want to do a power flush incase an old joint blows so don't know if anyone else got any ideas?

 

[Gotcha]

Is the return valve on the boiler open? I know its stupid but happened before.
Without circulation, the flow wouldnt get hot either and boiler would reach overheat levels quickly and shut down. Does this happen? Have you got a bypass anywhere, if wide open the flow could return before getting to the rads, but at least part of the return to the boiler would get hot. Dont bother with rad valves and changing rads, your concern is the main circuit itself and the point of return which is usually a radiator.
Find your last radiator on the circuit, disconnect it and bypass it with a hose. If it gets hot, you found your problem. If not, quote for new circuit.

 

[bacon_sandwich]

Recently had circulation issue and it was a big dump of air that was trapped after system pressure had been left to drop too long. It took a while to shift it by various means but thats all it was.

 

[Dkdc71]

Did you try fit a replacement pump sometimes it looks like the pump could be working making all the right sounds but the impeller can be broke away from the shaft

 

[zzzjim]

Was the system actually working , before it got sealed .
Some of the pipes may be gunked up/past it .
And as bacon_Sandwich put it , trapped air - a normal problem for not so well laid out creations -that have been drained down/left dry for a while !

 

[Ric2013]

Have you tried turning the pump up to max and turning off every rad except one? When that starts to heat up, try turning it off and then do the same with another radiator? I seem to have to do this every time I refill a system - lots of bad pipework practice and lots of airlocks in systems.

On a really bad one, I had to open the drainoff on the radiator while allowing water to flow in through one and then the other pipe - twice. Luckily, the radiator had Myson Matchmate valve with integrated drain-off.