Search the forum,

Discuss Boiler on Ground floor not sending hot water to Cylinder (coil) on 1st floor in the Plumbing Jobs | The Job-board area at PlumbersForums.net

Messages
10
Hi All

bit lost on an issue with an old back boiler - Open Vented.
Hot water circuit on Gravity (right side) and Central Heating pumped (left side)

Glow-worm Boiler on Ground floor not sending hot water to Cylinder (coil) on 1st floor. Boiler stat cuts out boiler on detecting over-boil.

However, Central Heating works fine when turned on.

Boiler F&E Tank Feed is free and works perfect when re-filling required.

Cylinder Flow and Return pipes (short horizontals) have been removed and mains water circulatd thru cylinder so no blockage in the coil.

Mains water circulated thru Boiler Flow and Return pipes (long verticals) so can't be blockage there.

The only way I can force hot water up the Boiler Flow pipe is when a slow stream mains water hose is attached to the draincock, fitted on Return pipe near the Boiler. This way Boiler stays on longer whilst heating up incomming cold water. Heated water rises up the flow pipe all the way to F&E Tank and does not enter the Cylinder coil.

Thinking about it, hot water will not entre cylinder coil and finds its way down via the Return pipe. Why I think? Because slow stream mains water hose on draincock must be sending 50% water to Boiler and 50% up the Return pipe, so no chance gravity hot water circulation can form.

When slow stream mains water feed via draincock is removed you would think that would kick-start the desired circulation but no joy. The whole circuit cools down. Boiler goes back to old tricks of cutting out due to over-boil.

Air-lock in the Coil?? - I tried slackening upper union (on Flow pipe) near the Cylinder but no joy.

Could I have some Advice on how to remedy this please. There must be a trick I am missing.

Thanks.
 
Hi All

bit lost on an issue with an old back boiler - Open Vented.
Hot water circuit on Gravity (right side) and Central Heating pumped (left side)

Glow-worm Boiler on Ground floor not sending hot water to Cylinder (coil) on 1st floor. Boiler stat cuts out boiler on detecting over-boil.

However, Central Heating works fine when turned on.

Boiler F&E Tank Feed is free and works perfect when re-filling required.

Cylinder Flow and Return pipes (short horizontals) have been removed and mains water circulatd thru cylinder so no blockage in the coil.

Mains water circulated thru Boiler Flow and Return pipes (long verticals) so can't be blockage there.

The only way I can force hot water up the Boiler Flow pipe is when a slow stream mains water hose is attached to the draincock, fitted on Return pipe near the Boiler. This way Boiler stays on longer whilst heating up incomming cold water. Heated water rises up the flow pipe all the way to F&E Tank and does not enter the Cylinder coil.

Thinking about it, hot water will not entre cylinder coil and finds its way down via the Return pipe. Why I think? Because slow stream mains water hose on draincock must be sending 50% water to Boiler and 50% up the Return pipe, so no chance gravity hot water circulation can form.

When slow stream mains water feed via draincock is removed you would think that would kick-start the desired circulation but no joy. The whole circuit cools down. Boiler goes back to old tricks of cutting out due to over-boil.

Air-lock in the Coil?? - I tried slackening upper union (on Flow pipe) near the Cylinder but no joy.

Could I have some Advice on how to remedy this please. There must be a trick I am missing.

Thanks.
Where about r u ? Could it be rocked up ? Rob Foster aka centralheatking
 
Where about r u ? Could it be rocked up ? Rob Foster aka centralheatking

RobFoster, thanks for looking.
I'm near Heathrow.
Rocked up?? I assume you mean pipes all scaled-up inside.

I too thought about this for a bit. Then I thought whats the chance a 28mm pipe getting blocked really bad.

However, I poured Sentinel X800 down from Vent pipe in F&E Tank, hitting the boilder all the way down the Flow pipe. Then I poured some via Feed hitting the boiler all the way down the Return pipe. Flushed it all out at least 6 times after leaving it to work for one hour. Judging by flushing water it doesnt look like/feel like there is a blockage or narrowing in the 28mm pipes.
 
RobFoster, thanks for looking.
I'm near Heathrow.
Rocked up?? I assume you mean pipes all scaled-up inside.

I too thought about this for a bit. Then I thought whats the chance a 28mm pipe getting blocked really bad.

However, I poured Sentinel X800 down from Vent pipe in F&E Tank, hitting the boilder all the way down the Flow pipe. Then I poured some via Feed hitting the boiler all the way down the Return pipe. Flushed it all out at least 6 times after leaving it to work for one hour. Judging by flushing water it doesnt look like/feel like there is a blockage or narrowing in the 28mm pipes.
No problems limescale where you are ...I will have a think
 
No problems limescale where you are ...I will have a think

I have read one or two posts about over-boiling the Boiler with temp-sensor removed. Not keen on this, given age of the Boiler.
Check this theory... when Cent'Heating is switched on, the same Boiler stays on much longer whilst the water is being puped around the CH Circuit. Would have thought under this condition there is enough hot water in the boiler to start climbing up the the Hot Water circuit Flow pipe - but it doesn't. (There is some heat on the flow pipe near the boiler but i think thats conduction heat only).
 
Mrafiq, you have a interruption/blockage in the circuit somewhere, it’s either caused by a plug of air or sludge. Do you have any of the pipework running horizontally?
 
Mrafiq, you have a interruption/blockage in the circuit somewhere, it’s either caused by a plug of air or sludge. Do you have any of the pipework running horizontally?

I have some pipework that runs horizontally indeed.
Boiler Flow & Retun (28mm) climb up the wall from ground floor, then horizontally in the ceiling and re-surface on the opposite wall (well just behind oppsite wall) for the Cylinder attchement in the Bathroom. Then from the Cylinder 28mm becomes 22mm as Vent into the F&E Tank in the attick. The other becomes 15mm as Feed down from the F&E Tank.

View attachment 150446

I have tried to attch a pic, hope its usefull.

Boiler_Hot_Water1.png
 
Mrafiq, you have a interruption/blockage in the circuit somewhere, it’s either caused by a plug of air or sludge. Do you have any of the pipework running horizontally?

I notice its easy to trap air in the coil if Flow&Retun re-fill quickly.
To reduce this risk I tried re-fill from draincock on the Return pipe adjacent to the Boiler using trickle-feed (slow run) mains water hose.
 
I’d hazard a guess, that is has a high point at the elbows where the pipes rise from the boiler... either caused by poor installation or the pipes have drooped in the middle.
 
In the worst case the pipes need to be either perfectly level or always a slight incline towards the cylinder
 
In the worst case the pipes need to be either perfectly level or always a slight incline towards the cylinder

I think you are onto something.
I am able to circulate mains water in the circuit ( did that when I had the Cylinder unions removed ) so blockage in unlikely. I was getting pretty good volume of water going and and water comming out.

So what would you say I do next?

Fill from the Vent pipe in the attick using mains water hose?

That will quickly saturate the Flow pipe. Water will enter Boiler and rise again via the Return and come up into the F&E Tank via the Feed pipe. There is risk that it will trap air in the Cylinder which looking at the pic, will be difficult to release.

Thanks.
 
Sort the root of the problem.... the pipework. Even if it means removing some ceiling or lifting boards. Removing air locks can be near impossible..... especially for a pro
 
Sort the root of the problem.. the pipework. Even if it means removing some ceiling or lifting boards. Removing air locks can be near impossible... especially for a pro

I take your point, and, Thanks.
Time for some drastic measures as anything else done so far has not been fruitful. If only Sentinel did X800-Air-Shifter :)
 
Could you cut a short length out of the vertical section from boiler? This will drop the elbows and make the horizontal section go slightly uphill instead. But as bogrodder suggests, this horizontal may have drooped in the middle - floor up and clip?
 
Could you cut a short length out of the vertical section from boiler? This will drop the elbows and make the horizontal section go slightly uphill instead. But as bogrodder suggests, this horizontal may have drooped in the middle - floor up and clip?


Thanks Ben-gee, good point.
Also scared a bit, recently found out 28mm straight connectors sold are metric and my 28mm could be imperial. its a well old system, I've had it for 20 years and this is its first fault.
 
Pretty sure 28mm and inch are compatible, same as 15mm and 1/2”. It’s 22mm and 3/4” that you need adapters for.
 
yep 28mm its only 22mm which is a problem
 

Reply to Boiler on Ground floor not sending hot water to Cylinder (coil) on 1st floor in the Plumbing Jobs | The Job-board area at PlumbersForums.net

Creating content since 2001. Untold Media.
Back
Top
AdBlock Detected

We get it, advertisements are annoying!

Sure, ad-blocking software does a great job at blocking ads, but it also blocks useful features of our website. For the best site experience please disable your AdBlocker.

I've Disabled AdBlock