central heating stress

[jase158]

went to a customers house last week as no hot water, I found a valve that would be restricting flow so replaced this, in the process I drained down and filled back up.
Boiler was and still is cycling on and off every 3-5 minutes.
I thought may be air but have pushed all air out and single rads getting nice and warm but not all together.
Is this something to do with boiler or is it sludge? System seems clean, clean water coming from rads, but doesnt always mean that it doesnt need flushing as I well know.
Boiler is downstairs and is at bottom of circuit so may be the sludge is building up in there but uncertain as system was working before last week.
I have tried opening the drain valve underneath boiler to push any air out of boiler but drain valve wont open, tried pushing out of the pump valves but these are letting by aswell.

So my options as I see them is

1. Powerflush (but not sure this will help and may end up pointless)
2. drain down, replace drain valve and pump valves and retry filling up again and see if this pushes air out
3. get a gas engineer in to replace a boiler part

Boiler is worcester bosch 30cdi, floor standing
System is open vented
boiler was installed 2 years ago

 

[acecharly]

Id get someone GSR in mate theres alot of things this could be several of which your not aloud to do.

 

[jase158]

but is it more likely to be the boiler, or more likely circulation?

or is it a 50/50?

 

[Nostrum]

Have you bled the vents on the boiler?

 

[jase158]

there aint one
thats what I'm edging towards air in the boiler but without a drain valve working I cant get it out

 

[acecharly]

Its hard to say without seeing it there seriously are so many things it could be pal. Circulation is obviously the problem but the cause is the issue. You may want to start with some sludge remover in the system see if that helps but id still advise you get someone in. Even by dropping the system and refilling it you may have caused more trouble than you reaise if you havnt done it rite.

 

[jase158]

but I dont want to go, replace a load of parts and then still not working

 

[PlumbBobBob]

but I dont want to go, replace a load of parts and then still not working

that's why you have been advised to get a gs chap in.(or chapess)

 

[Nostrum]

Agree with above, no disrespect intended but it sounds like you may be out of your depth. Sometimes it's better (especially for the customer) to admit defeat and learn from the experience than waste any more of your time and customers money attempting something you aren't familiar with.

Get an engineer out and ask if you can tag along and learn from it. What you'll probably find is that it is relatively simple to rectify but without the experience you could make a right pig's ear of it all and do you reputation no favours.

Hope you can see this as constructive criticism as it is intended, rather than a dig at you personally.