Potterton 1970s System - Lovely Hot Rads but not Hot Water?

[markymarkuk]

Hi Guys
Just wanted to check before I replace my copper indirect cylinder, that its what I should do?
The system is indirect coil, vented central heating using Potterton boiler from the 70s. The radiators work perfect. However, for the past year we have no hot water. It is a system that only heats the cylinder WHEN the boiler is on, this old system does NOT have the option of HW and Rads, or Just HW. So Im guessing no Y Switches etc.

Someone on here told me ages ago that the coil in the copper cylinder was probably clogged up, hence the reason Im going to change this. But just checking, I currently have the heating on, rads nice and hot in all rooms, when I go in the airing cupboard where the cylinder is, both the pipes that feed the coil are stone cold, both top and bottom on the side of cylinder. Is this correct diagnosis that coil is blocked. I would have expected that the pipe feeding the coil may still get warm? Or am I wrong?

Any advice greatly appreciated.

 

[TCCHeating]

Sounds like you have gravity hot water. Could be as simple as an airlock. If the coil is blocked, you can flush it out. No need for a new cylinder in my opinion.

 

[markymarkuk]

thanks for reply. it is a gravity system. I know how to bleed radiators to let air out, but how do you let air out of the coil in the cylinder??? thanks

 

[jackthom]

Does the boiler come on at all, however briefly, for water heating when the central heating is off?

 

[jackthom]

thanks for reply. it is a gravity system. I know how to bleed radiators to let air out, but how do you let air out of the coil in the cylinder??? thanks

Assuming there's no bleed valve you could slightly loosen the upper coil connector and see what comes out.

Untitled

• jackthom
• 18 Nov 2013
• 2

 

[markymarkuk]

Hi
The picture you attached is exactly what my system looks like. There is never any hot water not even for a short time. I will try loosening the nut you suggest tomorrow and let you know what happens. thanks

 

[ChrisR]

Look hard for a bleed point first. Old cylinder nuts can be tight and you can easily cause a leak which wrecks the cylinder. If the top primary (from boiler) pipe Tees into the cyl, and goes on up to the vent, you don't have an airlock. Not there, at least.

 

[twgas]

Have you checked that there is water in the f&e tank?

 

[markymarkuk]

Thanks to you all, I'm gonna tackle the job tomorrow (monday), in answer to your questions, the top inlet to the coil does have a T piece that goes straight to the loft, so no air lock I guess!!!!
Have checked the water level in the Feeder tank and there is plenty in there.

So will have to search elsewhere.. MMMmmmmm HELP!!!

 

[45yearsagasman]

Blocked cold feed? Try draining water from the system and see if the level in the exp tank drops. View media item 30811

 

[markymarkuk]

thanks pete. will try this, but when you say drain water from supply, is that from one of the radiators downstairs????

sorry for being a bit thick!!!!!!

 

[kbdiy]

That's what he is saying. By draining from any convenient point in the system, it should replenish itself via the F&E tank in the loft. If the tank doesn't empty and refill then you are looking at a blockage, probably where the fill pipe enters the system.

 

[45yearsagasman]

Apologies for not replying. Been out Christmas shopping