Rayburn Rhapsody backboiler+ immersion, CH still cold

[mickeysu]

Hi, I'm trying to figure out how my CH works as I've just moved into a property with a old installation from the late 60's. My problem is that I can get hot water from the immersion heater but I'd expect to be able to get CH from it too, but no joy.
One side of the boiler is connected for hot water, the Albion has pipe at top and bottom, fed from a large tank in the roof - all good there. The other side has indirect water heating attached to a small tank in the roof, the water is high on it. This side then goes down into the back boiler in the living room, which is a solid fuel 1969 Rayburn Rapsody 301 and then out the other side upstairs to a pump. From here I guess it's being distributed around the house. I'm trying to run the system with just the immersion heater, not the back burner. It should work right? The weird thing is that when I switch on the pump and the immersion heater, the hot water supply works but the pipe out of the Albion to the back burner doesn't even pretend to get warm. I guess it should though.
Any ideas????

 

[kevplumb]

the immersion heater only heats the hot water View media item 11263
the hot water and heating water don't or shouldn't mix

 

[mickeysu]

Thanks kevplumb, I thought the immersion could heat the CH via the boiler HW as well as the back boiler heating the HW via the boiler (yes crazy but)... Still confused about one thing though. Comparing my CH to this diagram

Untitled

• mickeysu
• 19 Oct 2010
• 2

it looks very similar. The drain cocks are basically on the radiators, and there's no way to bleed them for air.
I know that there is water on the supply side of the back boiler, but on the other side I've got a problem:
- If I turn the pump on, and turn off one of the radiator valves half (in the bathroom upstairs), I can hear whooshing through the valve, so there's water there.
- If I open up a drain cock on a radiator in the ground floor then nothing comes out, had a couple of drips. Feels empty to me...
- Someone did remove a downstairs radiator when fitting our kitchen 3 weeks ago and capped the feed and return pipes, but I checked before that there was no bypass next to it (unless it was built into the radiator), so that shouldn't be stopping the flow.
So how can there ever be water upstairs but not downstairs? I've left the pump on for hours in the hope that it would push water around the system, but it didn't change anything... All the radiator valves are on too...
(BTW what's a pipe stat, does it only pump when there is a temperature difference between the pump and the return or sth?)

 

[mickeysu]

I meant about the kitchen radiator, that the bypass must be under the top floor floorboards (the whole heating circuit appears to be in the 1st floor), so cutting off the radiator, which directly fed off the first floor should be OK.

 

[kevplumb]

(BTW what's a pipe stat, does it only pump when there is a temperature difference between the pump and the return or sth?)

the pipe stat stops the pump running till the boiler is hot to stop condensation in the boiler

also you might try bleeding the pump

undo the bleed screw and have a cloth handy View media item 17592

 

[mickeysu]

A colleague suggested that the bathroom radiator may be a bypass rad as is typical, and there may be a valve after it which is stopping water flowing to the rest of the system. Looks like a hunt under the floorboards a) for your pump suggestion and b) for the valve.

 

[mickeysu]

THe other thing I've been advised to look for is a separate feed from the header tank to the CH side of the Back boiler.