Bubbling water cylinder

[Englefield]

Hi all

I've got a system boiler and over the past month or so my water cylinder is making a huge ongoing bubbling, gushing and dripping noise when the water is switched on. This happens when the water is not up to temperature and the boiler downstairs fires up. The noise (which is loud enough to wake us up) only stops when the system switches off after hitting temperature. I've so far had the following work done in the last 3 weeks with no difference -

1) full powerflush, including de gunk of expansion tank
2) new cylinder thermostat
3) new boiler thermostat
4) 3 port valve head replaced and body checked
5) new heating pump power head
6) system bled several times - still air coming out of the cylinder bleed valve.

This work (other than powerflush) was done via insurance, but as the water and heating work, my insurance company are no longer willing to resolve this (home emergency cover).

The noise was never there before, and no settings have been changed. The joins for the pipes and pumps are all tight, and this is a 30 year old house so not a new system or layout. The cylinder is only 4 years old, it has an immersion heater which is not wired in.

Air is getting into the system somewhere it seems, but I'm stumped.

I have a newish shower pump and checked the connections there, all tight.

Does it sound like air is being sucked into the system? Anything I am missing at all?

Please ask any questions that will help to explain it more clearly.

Thanks

 

[lizard1975]

by the sounds of it air is being drawn into the cylinder via the cold water feed to it. In which case you need to buy a de-aerator (air separator). This removes the air from the cold feed to the cylinder and should solve the problem.

Have to admit mind that I'm not 100% sure here as this is old school set-up. not an expensive part mind or difficult to fit. If your getting a plumber in to look at it/fit it, then you want an old plumber who grew up with this system

Edit, could be as Andy says below, has the noise started since the new shower pump was fitted?

 

[HERTS P&D]

Has the shower pump being plumbed in correctly?

Post some pictures of the cylinder and pipe work.

Andy

 

[Englefield]

Many thanks for your replies. The shower pump was fitted 10 months ago, and the noise is very recent (3 weeks or so). The only water related issue I did have recently was a slightly leaking flap valve in my toilet cistern, the water was constantly refilling. This sort of seems fixed, is the toilet anything to do with the water circuit (sorry I'm not a plumber!)

The water is working fine, so the hot water is good and there doesn't appear to be any leaks. I have noticed that the wall mounted shower on / off valve does sometimes get loose (but no drips underneath).

Anyway here are some photos..

Shower pump - had no problems with this


Bottom of cylinder (approx 4 years old)


Middle. Note the bleed valve is quite low. I have bled a fair bit of air from this. This has always been here and have not had problems in the past


Top


The expansion pipe does get warm, but as mentioned the noise starts immediately even on a cold tank. It will continue gushing, bubbling and sloshing for as long as the boiler is fired up.

Does this help?

Thanks for looking guys

 

[lizard1975]

Have you had work done on your boiler lately, and is it also an open vented boiler (no filling loop)? Also do you get any banging noised from the radiators/pipework when only the heating is turned on (no heating to cylinder)? PS toilet has nothing to do with it

 

[HERTS P&D]

Does the shower pump only pump hot water?
Does the shower have cold mains going straight to it?
Have you checked water in the 2 tanks in the loft?

Andy

 

[Englefield]

I've had no recent work done, it was serviced about 6 months ago and a new PCB about 9 months ago. It's a potterton suprema 40l, not sure if its an open vent system, a quick google looks like it might be?

The noise only occurs with the water on - when the heating is on there is no noise from the cylinder.

 

[Englefield]

Does the shower pump only pump hot water?
Does the shower have cold mains going straight to it?
Have you checked water in the 2 tanks in the loft?

Andy

The shower pump does hot and cold, it was added in as the shower head is quite large.

I haven't checked the tanks myself, but the man who did the powerflush on Tuesday went up there and checked it and cleared some sludge out from the small tank.

He said that he thought the noise was caused by air going up into the tank and being forced back down by the sludge, but the noise is still continuing now after the tank was cleared (just the small expansion tank). I'm not sure what he did (if anything) to the large tank.

One thing I haven't yet tried is being in the loft when the bubbling noise occurs, should there be something I should look out for? The expansion tank is directly above the hot water cylinder.

 

[lizard1975]

Could be either type sealed or open vented, but my guess would be that it is an open vented boiler.

As you say that you are often bleeding the air out of the pipework by the cylinder (and i take it not having to top up the water to the heating pipework of the boiler), then i think i know the fault!

By the sounds of it you have got a leak somewhere on the heating pipework, and fresh water is constantly being drawn in via the feed tank to the boiler. Every time water is drawn in to replace the lost, some air is drawn in at the same time and collecting in your cylinder causing the noise when heated.

Two options, find the leak! Can be easier said than done
and or fit a air separator, that will remove the air from the fresh water being pulled in each time and stop the noise as a result.

 

[Boilerman2]

On the picture of the cylinder, and the primary bleed point, it looks to me like the bleed point is connected to a point LOWER than the flow connection to the cylinder, this will be trapping a fair amount of air in the top of the primary coil, no doublt in my mind that this is where the problem lays I would get an old bath towel under the cylinder and carefully crack open the union to the primary flow, letting the air out (unless you are extremely competent I would not recommend you to DIY this) it would be best to re-pipe to ensure that the bleed point is at the highest point on the pipe work

 

[Englefield]

Thanks guys, yes I've been advised that the bleed valve pipe isn't in the best position, so will look to get this moved higher up, there is plenty of room.

As for an air separator, I've seen this, is this the right part -

http://www.toolstation.com/shop/Heating/Central+Heating/Air+Separator+22mm/d230/sd2708/p75473

I'd be getting someone in to do this, bleeding radiators is about as technical as I get.

As for finding a leak, I know it depends on the design and layout of my house, but is it common to have pipes fully concealed in walls? I can access under floorboards but does leak discovery become a bit of a nightmare due to pipes being in walls and under concrete floors, and is it common to have leaks in these hidden places?

Another small fix I did a few weeks ago was to replace 2 bleed valves on downstairs radiators as they were busted, but these are fixed now and the noise continues.

 

[lizard1975]

Yes that the one (but their are many different designs out their)

Check your bleed values that you replaced, they can be a **** to seal sometimes

As to pipes being hidden in walls yes it is common, but has gone out of fashion of late with the problems of having to use such small pipes can cause.

Edit Re Leaks, their often were the pipework joins the radiator so check all the connections. Look for stains on the copper pipework or rust at the control values