No Circulation to radiators

[Pooly89]

Hi guys,

Basically I have a customer with a system which is ancient(old 4 pipe back boiler unit as far as I can see) and he was complaining that the boiler would only fire for a short period then shut down but rads weren't getting hot(bad circulation due to pump found to be not moving).

so in short what I have done is to replace the pump (obviously), but due to system design I am unsure whether I have it in the right way, there is obviously no 3 port/two port valves etc(see picture). but a problem seems to still be lying with poor circulation to the radiators. I have not tried back charging a air lock as I don't believe this is the cause(not ruling out though) Just wondered if any one had experience with these types of systems and could point me in roughly the right direction.

also system when drained didn't appear to be overly dirty and pipework to pump almost completely clean.

 

[EPH]

What did it refill like, is that a combined feed and expansion?

 

[Pooly89]

Refilled fine all vented fine as well, no it's not got a combined feed & expansion...

 

[Pooly89]

No one got any suggestions then....:banghead:

 

[jtsplumbing]

Pump needs to point down, is the gate valve (22mm) open ? poss its faulty replace with full bore leaver valve

 

[Pooly89]

pump is pointing down, I'm not 100% on whether the gate valve isn't causing a restriction but temp seemed to be spiking when hand placed on the pipe under it. is there any reason to replace it, is it actually needed?

 

[jtsplumbing]

Yes old system, gate valve is used to turn off heating system in summer, so would be better to replace with leaver, Better still upgrade to a 3 port valve, cyl stat, and other controls rewire etc. depends how much they want to spend, But change gate valve !

 

[Pooly89]

Yes old system, gate valve is used to turn off heating system in summer, so would be better to replace with leaver, Better still upgrade to a 3 port valve, cyl stat, and other controls rewire etc. depends how much they want to spend, But change gate valve !

thanks JTS

I have changed the gate valve for a leaver valve and it was pretty much completely closed, still have a problem with circulation though as one rad gets hot but only at the very top(pins were stuck on all trv's) and a few others get mildly warm. I am going to change one of the trv's tomorrow and assess whether it's worth doing all of them and treating the system to try and shift any restrictions in the MICROBORE pipework. I have advised that the system is in dire need of replacement but I believe the customer is making it a case of if can get the system running for now then change the lot in the new year... seems like a waste of money to me though :/

 

[Reg Man]

Microbore? That's your answer. It can't be power flushed effectively. I would be recommending a re-pipe f the microbore and update on the controls, with a strong recommendation that a more efficient boiler is installed. May be beyond what the customer expects, but that's the way it is.

 

[jtsplumbing]

thanks JTS

I have changed the gate valve for a leaver valve and it was pretty much completely closed, still have a problem with circulation though as one rad gets hot but only at the very top(pins were stuck on all trv's) and a few others get mildly warm. I am going to change one of the trv's tomorrow and assess whether it's worth doing all of them and treating the system to try and shift any restrictions in the MICROBORE pipework. I have advised that the system is in dire need of replacement but I believe the customer is making it a case of if can get the system running for now then change the lot in the new year... seems like a waste of money to me though :/

Well if money is tight remove & flush out Rads, put a good heavy duty cleaner (F5) in system , leave running for a week on high temp & see if it improves.