Radiator head scratcher

[BenLewis]

Hi wise folks,

 

We have quite an old set-up in quite an old barn, I’m thinking it could be partially blocked.  We moved in during summer - so have not needed to use the system.  After a few let downs on plumbers on our oil boiler, we’re testing ‘plan B’.

 

The central heating was drained of water (due to a leaking radiator).  We refilled the system and bled all air out of the system,  all radiators filled with water.

 

We fired up our multi-fuel boiler in the basement yesterday to test out the central heating system (We also have an oil boiler on the system, but it’s due for replacement and disconnected from oil).

 

The stove got up to temperature and the Grundfos pump started pumping (after a replaced fuse).  So far, so good.

 

Most radiators on the ground floor are super hot, three remain ice cold (including pipes either side).  Upstairs all radiators cold.  Immersion cylinder upstairs producing hot water.

Valves on radiators all seem to be open.

 

After a short while I heard noise from the radiator header tank, which seems to be simmering - steam coming off it.

 

I can’t trace the pipes to the cold radiator as in the floor, but they must be connected as they filled.

 

My thoughts are as it’s quite an old installation (decades old) that a pipe is blocked somewhere.

Any help / thoughts / investigation tips appreciated!

 

Cheers,

 

Ben

[dpmiller]

Sounds like the hot water circuit might be gravity, how many pipes go to the multifuel? Or is the system "pumping over", with the pump forcing water out of the vent pipe and back into the F&E tank?

Are there any other pumps, like beside the oil boiler?

 

You might try as a first go, closing  the valves on the hot radiators to force the flow to the others. Once you've flow to all than you can worry about balance...

[BenLewis]

Thanks for getting back quickly -

 

there are 2 pipes (1x top and 1x bottom) at the multi fuel, both then connect onto 2 pipes, like they’re on a circuit (picture attached if that helps).  Following the visible pipe work, it looks like it’s all joined to the same pipe work as the oil boiler.

 

There is a pump by the oil boiler - it’s wired into old Honeywell control box.

 

cheers,

 

ben

[ProDave]

Try shutting off all the radiators and opening up one at a time to see if you can get water to flow to each in turn.  It might just be an air lock.

 

How is the multi fuel boiler joined to the oil boiler, usually there is a neutraliser or low loss header.

 

Can you turn something on to get that pump running?

[BenLewis]

Thanks ProDave,

 

It looks like it’s plumbed straight together - top pipes are joined and so are the bottom, nothing that I can see in between.  They’re in different parts of the basement - so a little tricky.  I’ve drawn as best I can how they’re joined up from following the pipes around.

 

Once up to temperature - I’ll try the radiators one at a time.

 

cheers

 

Ben

[BenLewis]

The 2nd pump doesn’t seem to be interested in running.

 

also - when turning on the radiators one at a time, only the same ones warmed up - that is until a couple of the taps/valves on the radiators started leaking quite a bit- not sure they been turned for some years.

 

Back to draining the system for a bit.

 

cheers,

Ben

Edited October 20, 2019 by BenLewis