Boiler and CH problems

[Mottie]

Surely any cleaner in the system will only work while it is able to flow past a partial blockage? If the system has a solid blockage of magnetite, no cleaner will work as it is unable to flow where it is blocked. I'm not sure but aren't you supposed to find the blockage in a pipe (usually where there's a bend) with a magnet and then cut out and replace that section?

 

[DP]

Take it out and flush it right away, it will eat your pump bearings and if you have any weak points on your rads they will pin hole, you should have used X400, X800 should never be left in the system

X800 will indeed effect pump and I have seen this first hand, but not if a thorough multiple fill and empty is carried out as per makers instructions. Have used X800 many times without issue as gave always removed the system water post cleaning.

A few years ago asked a local engineer who only does installations to chemical cleanse a system. He used X800 post which the pump started failing. The system had not been blushed as per requirements. Asked him to go Bach and do it as per suggestion. Same pump still working away now.

Remember when you open the drain valve to dump the system water and pressure goes to 0, does not mean system is empty as there will be remnants of cleaning chemicals in the system. X800 is a rapid cleaner, either carry out multiple fill, run the pump to mix fresh fill and residual system water to dilute everything and do this until water dumped is clear or with boiler run at low temperature tackling one radiator at a time, do a slow release of water dump at the drain point. This way fresh water is diluting what is circulating in the radiator. When water clear close that radiator and move to next.

Any leaks in the system post cleaning may well be due to X800 clearing out the sediment which previously was acting as a sealant

Fernox had a similar cleanser DS40

 

[DP]

Are you asking if hot water is discharging back into the expansion tank in the loft? I'm not too sure to be honest. The pipe is quite hot, and one of the tanks (either water or CH) is definitely overflowing as there is always water outside where the overflow pipe comes out but I can't tell which one it is?

Get this issue resolved else system sludge will be a constant problem

 

[BlueLoo]

Did you read that thread?

I will suggest:
1) When you drain the system and flush it, remove all the rads and flush them out in the garden with a hose. You may be amazed at a t the crud and it will really help with general flow and heat transfer.
2) Clean out your head tank when it is empty.
3) You seem handy enough, remove the pump and clean up the impeller. (may not be needed but heyho)
4) Set the pump back to speed 1.
5) Do a general review of the system, look for leaks, problems etc and see if you can or need to do any further preventative actions.
6) Flush through and refill. I wouldn't use inhibitor just yet because.....
7) Check to see if the head tank is overflowing still.
8) if it is still overflowing and your boiler is still misbehaving, you may need to get the plumber to replace the FE branch piping or where the magnets sticks.
9) If not, put in x400 as per the link thread and leave for a month, drain, flush and add inhibitor and see how you get on.
10) Set the pump speed correctly anyway as any cleaning will affect it.
11) YOu probs don't need powerflush if you do all that, and many plumbers ddon't believe it works anyway.....

The plumbers here may suggest other things, this is only my DIY thoughts.

Best of luck.

 

[DP]

If not, put in x400 as per the link thread and leave for a month, drain, flush and add inhibitor and see how you get on.

Seek advice from the makers. A month? You cannot be serious.

 

[V1k_10]

Get this issue resolved else system sludge will be a constant problem

I went into the loft and neither the water or CH header tanks are anywhere near the overflow level. But at least one of them is definitely leaking.... Other sitting there waiting, is there any easy way of working out which it is?

 

[Hugh Jaleak]

I went into the loft and neither the water or CH header tanks are anywhere near the overflow level. But at least one of them is definitely leaking.... Other sitting there waiting, is there any easy way of working out which it is?

Was CW Storage Cistern full, (i.e. not filling to replace water used in a draw off in the house?) I'd hazard a guess it is the F&E Cistern thats your culprit, if the CH system is 'Overpumping' due to issues with the system, it will fill from the vent pipe faster than the water can get back into the system through the cold feed, (especially if Cold Feed is blocked to some extent), so overfill and excess water escape via the overflow.

Level will then drop once things settle down (or system switches off), and refill from the Ball Valve, before cycle repeats next time the system kicks in.

 

[HERTS P&D]

Seek advice from the makers. A month? You cannot be serious.

DP, you don't need to argue with the Diyers! It's just a shame the mods don't keep on top of it!

Andy

 

[V1k_10]

Was CW Storage Cistern full, (i.e. not filling to replace water used in a draw off in the house?) I'd hazard a guess it is the F&E Cistern thats your culprit, if the CH system is 'Overpumping' due to issues with the system, it will fill from the vent pipe faster than the water can get back into the system through the cold feed, (especially if Cold Feed is blocked to some extent), so overfill and excess water escape via the overflow.

Level will then drop once things settle down (or system switches off), and refill from the Ball Valve, before cycle repeats next time the system kicks in.

I checked both tanks before I put the x800 into the CH expansion tank and both were refilling as would be expected? There were a lot of large creamish scrapings/bits in the CH tank which i cleaned out too though so not sure if that means anything?

 

[Hugh Jaleak]

I checked both tanks before I put the x800 into the CH expansion tank and both were refilling as would be expected? There were a lot of large creamish scrapings/bits in the CH tank which i cleaned out too though so not sure if that means anything?

From your description so far, it appears you have some sort of blockage in the CH system, which is not uncommon in systems that haven't been correctly dosed with Inhibitor. The various metals used in the system react with the water, creating magnetite sludge, which blocks rads and pipework. Usually not noticed until there's an issue, such as that you are now describing.

What can happen is, the pump is trying to move the water around the system, but if pipework becomes blocked with crud, the water will take the path of least resistance, which can be, (rather than around the radiators as required), straight up the Vent Pipe, and thus discharges into the Feed and Expansion Cistern for the CH system. As I described above, the cistern than rapidly fills from the vent pipe and overflows.

Can you put up some pictures of the pipework you have, including the pump and any motorised valves please?

 

[Dereekoo]

if the CH system is 'Overpumping' due to issues with the system, it will fill from the vent pipe faster than the water can get back into the system through the cold feed, (especially if Cold Feed is blocked to some extent), so overfill and excess water escape via the overflow.

.

Impossible to happen as the pump suction cannot magic water from somewhere other than cold feed from header tank therefore equilibrium must be maintained in the header tank i.e. that is, in = out, and TWL will for all practical purposes remain the same.

I would question what the OP means when he says there is always water outside below the tank overflows but cannot see which one its coming out from, my guess is he means there is a damp patch which is due to drops of steamy water condensating in the CH overflow pipe due to the tank containing hot water due to the vent pipe discharging into the tank. It would be nice if the OP could confirm what is happening in the tank and vent pipe when the central heating is switched on and running.

.

but if pipework becomes blocked with crud, the water will take the path of least resistance, which can be, (rather than around the radiators as required), straight up the Vent Pipe, and thus discharges into the Feed and Expansion Cistern for the CH system. As I described above, the cistern than rapidly fills from the vent pipe and overflows.

Again impossible, try turning off the isolation valve after the pump i.e. so the system is completely blocked, no flow whatsoever will discharge from the vent pipe as since the pump is not pumping anything it cannot discharge anything. The only time flow is sent up the vent pipe is if there is a restriction between where the vent pipe spurs off from the suction pipe leading to the pump and the cold water feed pipe that spurs into the suction leading to the pump.

As stated in posting nr 4, things have been discussed in depth on various central heating problem in the following thread, posting nr 67 being relevant
https://www.diynot.com/diy/threads/hot-water-flowing-from-vent-pipe-into-loft-tank.583252/

 

[Hugh Jaleak]

Impossible to happen as the pump suction cannot magic water from somewhere other than cold feed from header tank therefore equilibrium must be maintained in the header tank i.e. that is, in = out, and TWL will for all practical purposes remain the same.

I would question what the OP means when he says there is always water outside below the tank overflows but cannot see which one its coming out from, my guess is he means there is a damp patch which is due to drops of steamy water condensating in the CH overflow pipe due to the tank containing hot water due to the vent pipe discharging into the tank. It would be nice if the OP could confirm what is happening in the tank and vent pipe when the central heating is switched on and running.



Again impossible, try turning off the isolation valve after the pump i.e. so the system is completely blocked, no flow whatsoever will discharge from the vent pipe as since the pump is not pumping anything it cannot discharge anything. The only time flow is sent up the vent pipe is if there is a restriction between where the vent pipe spurs off from the suction pipe leading to the pump and the cold water feed pipe that spurs into the suction leading to the pump.

I would suggest you do some research on Overpumping.....

 

[V1k_10]

Thanks all, I'll take pictures and put up tomorrow

 

[Dereekoo]

I would suggest you do some research on Overpumping.....

I'll hang my hat on the hydraulic explanation in posting nr 67 and 40 years in the water industry and an understanding of Bernoulli,Colebrook White, et al (my research I guess?) but, based on your experience and hydraulic knowledge, please feel free to put forward any logical counter arguments to the "theory" put forward as opposed to a nothing reply which doesn't explain/support any of your interesting statements, which, I think could be the answer to the world water shortage i.e. suck water from no where and discharge into a holding tank

 

[ianmcd]

since the pump is not pumping anything

It is not a pump, it is a circulator, it does not PUMP anything at any time