Sealed system cylinder coil leak?

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Hi,

Have started to have to keep topping up the level on a sealed vented system (I think that's what it is - conventional boiler plus cylinder, cylinder vents into cold water tank, boiler and cold in loft, HW cylinder ground floor).

The system runs ok on heating but switching on HW at 430am I can hear the pump struggle when it goes below 0.5bar. I guess when the heating comes on it equalizes the pressure a bit more, but always the HW is where the low pressure causes the pump to whine.

This morning I topped up from 0.5 to 1.0 and checked just now. Was just below 1.0, HW had gone off and CH would have been on and off since. Put the HW on advance and immediately dropped to 0.9. This suggests to me pressure in the HW had been dropping while it was off, by 0.1 per day+ would make sense.

Some valves on the system show some weep - 3 way needs changing I think and pump valves - but that wouldn't impact HW only.

As I can't see any leaks anywhere - other than on the 3 way when I changed the actuator recently and I don't think that's enough to cause this? - does the coil seem the most likely suspect?

System will be about 15 years old now. Stopped using the immersion heated a while ago and water is soft but what else could it be?

Cheers!
:D
 
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Replace 3 way valve if it is leaking and replace pump valve as well if leaking.

Do that first. Leaking valve is enough for pressure to drop.

Daniel.
 
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If the coil is split you usually get discoloured hot water. Those that i've found if you leave overnight, the heating pressures gone and the HW storage tank has risen and overflowing. P.S. Doesn't take a massive leak to see a noticeable drop on a sealed system.
 
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Cool thanks gigz. I got the valve with the actuator but didn't change it yet. Will look to do pump valves sames time since last did them about 7 yrs ago and noticed a drop of water a while ago...
 
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Hi, I haven't done this yet. Just wondering if a weeping valve is still most likely given I'm having to top it up every day by 3/4 bar, ie by the of the day its dropped each time to 0.25. Is there anything else I can check?

Will deffo have a go this weekend as getting seriously ff'd off. Will close off all the rads, drain, switch valves, refill and check has worked.

If so will fernox it the following weekend with a full flush etc.

Cheers!

:D
 
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No water in the EV but it may be low pressure. Understand I need to check pressure level when the system is completely depressurised but my bike pump doesn't make this easy...
 
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Why did you not use the old nuts and olives ? johnd would be proud of you with all that ptfe ;)
 
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Gah, the pipes were minging, I thought it would never seal if I didn't clean it up :p

Reckon now the pump is fooked. Got some x400 in at the mo -- rubbish new format, what's wrong with the tube in the gun method?? Nozzle for the bleed screw didn't even fit, had to put it in the feed loop....

At least on the plus side not losing pressure so that must have been the old three way. So when I drain the x400 will probs fit a new pumps and valves then.

Cheers!

:D
 
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Everyone always says to change the gate valves because they'll leak, well the peglers I fitted 7 ish years ago didn't leak. I still couldn't get the pump out though because it had rusted to the top valve.

Probably could have broken it off with a larger wrench but in the end had to drain the system anyway, rads all closed again, take it off with the valve and smack the end of the wrench with a hammer while it was on the floor.

PITA but got there. Old pump clearly rusted on the inside. I wasn't able to bleed it either so I guess it was clogged and had been running progressively slower I think for years.

And the new pump is.... the new cheap garbage Parker pump from Amazon for 39.99!!! Very sceptical at first. The switch from 1-3 came undone went I opened the case and I had to work out the correct orientation when it was running. Thankfully I don't think it could have gone >3 or <1. Not 100% sure though..

Was noisy to begin with but then it ran clear. Was easy to bleed though the screw is very short. Was aware of this in advance from the Amazon reviews. Was also an exact perfect swap for the myson so couldn't have been easier.

And now it running sweeeeet and all 8 rads are red hot, with the water, on number 1 in a 3 story house.

So, apart from the frustration of the RIDICULOUS X400 applicator things are looking better... Will run the remainder of the X400 then do a quick dose of Fernox I think then some inhibitor at the weekend.

And buy a bigger wrench.

:D
 
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