Water Cylinder noise issue

malexicon

Very little change in the boiler pressure when its firing up and running, hugs the 1 level pretty well - I did notice it increased a bit when the CH fired up a few weeks ago, but not much. Thanks for that re the mains/system pressure - I can rule that out now.

Cycle 2 for the day has come and gone - no loud bang this time (this is a 30 min cycle rather than 45) though I did hear it making a bit of a noise a couple of mins before the end but more of a tap and not much louder than the motor from the motorised valve when it came on to close the flow at the end of the cycle... its almost like it knows when the cycle is about to end - as I said - baffling - but the fact that doesn't happen every time, or more than once generally in a cycle at least gives me some reassurance.

NSG666

Sounds like those gate valves got shut off when you had the bathroom refurb done and they have either not been opened up enough or they might have snapped internally so, although the wheel will be fully open the gate will be stuck. Explains why no heat going to unvented coil when both systems open and also the banging when only going to the coil as water is not getting through the boiler quick enough.

Edit: On the flow pipe to the how water coil there appears to be a bleed vent just at the top of the pic. When the heating system off and cold, open the bleed screw to remove any trapped air.

malexicon

Thanks for that NSG - it certainly seems like that may be what has happened - it would make sense for the bathroom guys to have had to stop water or whatever and if valves have only been partly opened once they were done, I can see how the flow to coil would be restricted and, of course by nature of the fact that this is an in and out type set up - the flow would be similarly restricted on the way out regardless of how open the valve here might be. Likewise the flow out to new shower/hot taps etc would be fine (which it is) as above as its the (now improved) mains pressure that pushes this out. Its certainly not a big job for my G3 guy to look at when the cylinder is being serviced

The bleed vent you mention is actually on the pipe next to the flow one - its my bad photography here sadly....

I appreciate you, Bendy and Rodders helping me here.

Rodders53

Those gate valves _may_ have been installed as a means to isolate the HW coil when the new cylinder was fitted around a year ago?  Thereby allowing the CH radiators to work while the install was carried out?  They look fairly new?  (Some original HW tank pipe was painted silver on one pic).  

It is unusual to have such isolators in a heating installation that's clearly (at least now) S-plan;  but they can aid maintenance / isolate faults.

They should, imho, be fully open (but turned back a 1/4 turn to prevent 'sticking' a la stop valves) to permit full flow through the coil when HW heat is called for.  But then I didn't design the system.

Absolutely no reason for a bathroom refurb plumber to touch those (other than in error) as they don't control the hot or cold water supplies.


PS really stupid place to put the mains electrical connection box, under water pipe connections.

malexicon

Hi Rodders - agree re the box - Its always been down there as far as I know, far from ideal. Another thing to try and get attended to.

I looked back and have a pic of the old set up - before the new cylinder went it - no isolators other than one which I believe was attached to the cold inlet so you are spot on - this appears to be new work (admittedly the set up below is much different from the new one) - and it would seem likely they have fitted it like this for isolation purposes in case any future work or servicing was required.

I'll ask my G3 plumber to check these as part of the service or as a side job if I need to - if there's a big fix, or its a pump issue (which I dont think it is as we do have CH and HW but admittedly with issues) then BG/Dyno can come back and sort out as part of their service plan and I'll at least have had a good run through with the G3 plumber in advance. I'm hoping as you say this is a straightforward job, just opening everything up which may have been restricted in error by the bathroom fitters - hopefully as the valves are new they should turn nicely.

Thanks again for your assistance and thoughts which will help me in a conversation with both my G3 servicing plumber in a couple of weeks timeh BG/Dyno a little further down the line.

malexicon

I thought I would add a wee update after my cylinder was serviced today. G3 plumber was great, had a good talk about things and, somewhat helpfully, he heard the noise as the cylinder was heating up. The flow into the cylinder was being restricted by the by-pass valve (operated by a red gate wheel valve) being almost fully open. Thus it was grabbing a lot of the water before it got near the cylinder. After he adjusted this the cylinder was getting its supply quite well and it did get up closer to temperature much more quickly after a while. After the adjustment to the bypass we could hear the air in the pipes whooshing around, there is also air in the radiators. 

Next step is to evaluate over the weekend, see how things settle down (the cylinder did make its usual one off noise in its evening cycle sadly) and, most probably bleed the radiators to see if we can get air out there. Depending on how it goes next few days they will drain the cylinder and central heating systems completely to try and get rid of any air.

I think the issue with the bypass stealing the water has not helped us at all and exacerbated any air issues which, I guess may have been introduced at some point when new shower / radiator went in (I am guessing a bit here on that front...).

So feels like some progress made, though we are not there yet... I guess the key here is that what may have been the main contributor has been sorted (the HW and CH can run at the same time now) - now we wait to see how it goes, and then, most likely, if this can be sorted with the total drain down and refill.

Thank you all again for your help and advice on this.

Bendy_House

Thanks for the update, and pleased it's getting there.

The 'air' issue is a weird one - air is usually easy to get rid of, either by bleeding rads, or it just happens automatically from an air valve either external or from within the boiler. (Not sure how draining the system down fully will remove air?)

Keep us posted on this, please

malexicon

Hi Bendy,

Thanks for continuing to show interest in this - I think, after reading your comment and thinking back again to the conversation with my G3 that what he was really asking us to do was see how it settled next couple of days, bleed the radiators and then give them a call back after that. I kind of presume that the draining is more related to the tank than that radiators, though I think what he suggested was they'd do both and try and create some better bias.

Interestingly, after the adjustments were made yesterday my wife suggested that the heating seemed to work faster and it appeared to me that the radiators stayed warm for longer after the thermostat had switched the CH off... now that may be a bit of wishful thinking, but certainly the temp in the house was reached a bit quicker first thing this morning (according to Hive) - so there may be another benefit to all this.

The morning cylinder cycle has come and gone and there was no banging noise which is good but the previous noise was somewhat sporadic anyway, however we can clearly hear air moving around the pipes alongside water, particularly when the HW is on. When the CH is on there is some initial gurgling, but this settles down. My guess here is that the air is being pushed around, but it has longer to go when it is running through the CH so is less noticeable.. I could of course be talking nonsense here (and probably am)

What the G3 plumber said it would be easier to get the air out of the rads, indeed, when both CH and HW were on at the same time it seemed as if some of this air noise moved across to the rads from the cylinder. I'll take him at his work regarding letting things settle over the weekend and evaluate but suspect early next week I will bleed the radiators to try and get some air out. Only one rad was bled yesterday and that certainly produced some air, the pressure on the boiler has dropped too so I will need to repressurise this. On this subject I havent repressurised a boiler before. I know that I need to ensure the boiler is switched off and cold before doing so but again, showing my ignorance on this can I ask a quick Q on this process... I have a filling loop under the sink for this. It has two valves - one is a screw driver slot on, one has a plastic handle. Would I be correct in thinking I need to turn these anti-clockswise to do this? I presume that the black handle should be parallel with the pipe its on to open the valve and similarily, the slot line should be parallel to the other pipe?

Thanks again for all your help.

Bendy_House

I'm not surprised that the CH is also heating up more quickly, as your issue seemed to have been that the manual by-pass was too open. This would allow some of the HOT water coming out the boiler, to immediately RETURN to the boiler via that valve, and avoid the more difficult routes such as the hot cylinder coil, and the radiators!

By partially closing that valve, more water is being directed to go where they should be - rads and cylinder.

I wonder if there's any mileage in fitting an 'auto' by-pass there? These are cheap, and will effectively close off that by-pass fully UNLESS there's a reason for it to open, such as all the rad's TRVs being closed.

The air seems to be in the 'system' water. This is the water that keeps circulating around the boiler, the radiators and the hot cylinder's heating coil. This does not mix in any way with the hot water that's stored in your cylinder.

As for repressurising your system, yes these are the two valves to use. However, these need opening slowly and not fully, or else you risk over-pressurising it.

First, what pressure is it currently at? You ideally want it at around 1 bar or slightly above - say 1.2-ish. You'll want to top it up if it falls to below, say, 0.9bar. When you bleed out air, the system pressure will usually fall, so will usually require a top-up.

Ok, you have two valves - one 'slotted screwdriver' and the other is a plastic handle.  For both, you should expect the valves to be OFF when the slot or handle is at right-angles to the valve's body.

IF your system needs a top-up, this is what to do; first slowly open the slotted screwdriver valve until it's fully open - whilst listening for the sound of hissing water. It should open up fully (yes, a quarter-turn, until parallel to the valve body) without any water passing.

Now, equally-slowly, start to turn the black handle. As soon as you hear the hiss of water, don't open it any further, but observe the pressure gauge. If you can see it start to rise, that's fine - just let it until it hits just over 1bar. Then turn the handle off again fully, and ditto the slotted valve.

If there's a hisss of water but the gauge is barely moving, then tweak the handle open a tiny bit more.

What you don't want to do is open them both fully, because there's a chance you'll shoot over the level you want! If this happens - if you go 1.5bar or above, then just bleed a rad to lower it slightly.

malexicon

You're a star Bendy - thanks - I'll take my time doing this and my wife can help me keep an eye on the pressure gauge as we go along so we dont go too far - your kind advice as to what valve to do first etc is really helpful for me too. The pressure will certainly need to be topped up - looks like the pressure is virtually zero at cold and gets to around 0.5 to 0.7 when the boiler has cranked up fully. I had around 1.2 in my mind to take it to, putting it sensibly in the green zone so thanks for suggesting that kind of level.

Thanks also for your comments on the system water vs tank/shower/tap water - for many of us we have little understanding of how things really work, but with you and others help and some digging around its become a lot clearer. The water stored inside the tank and system water never mix, so now its a case of trying to get that air out - ideally through the radiators given its easier to get into them. One last Q on that front - should I start bleeding at the top of the house a( (just a 2 storey house) and work my way down or does it not matter?

Its been a strange few months trying to work this one out and I still do wonder quite how it got this bad. It may have been when the ensuite was changed and part reconfigured - it certainly seemed to have gotten worse after that... In saying that I have barely touched the radiators over the years to get any air out - so I've really not covered myself in glory if my own ignorance (and reliance on BG's annual service to tell me everything is good) has not helped. Once I have re-pressurised for the first time it will give me the confidence to try and do these things a bit more often for sure... given the amount of air that seems to be firing around the system pipes around I'll probably have to do it more than once in this process anyway!