Hot water issue

[CJC]

Dear all,

I wonder if you can help.

I am having issues with my hot water, in regards to water pressure. Long usage will result in the water chugging as though an air lock wants to form. Or showers (which is a mixer tap, not power or electric) are so weak and frustrating.

I remember my system running fairly adequately when I first moved in but not no longer.

Things that have changed since:

- New boiler, pumps and controls Heating system consists of tank in loft, cylinder upstairs (original one), boiler downstairs and bathroom downstairs only.

- New washing machine which is now cold fill only (no idea if its related but as it no longer uses the hot fill, I thought I=92d add it in)

Now I have called in someone to check the issue and each time it has happened they remove the lock by either draining the system or sucking it out with a hoover. However, just a few weeks later the problem comes back.

I wonder if there is anything I can do to improve the situation. Am I right in thinking the issue is related to lack of pressure in the hot water??

Any help would be greatly appreciated, as I am going mad with the current situation.

[SS]

It's probable that someone has installed your hot water pipe with a high point that fills up with gases/air that are dissolved in the water. I say this because they are able to suck it out. You have to look at the pipework and see if you can imagine a place where air/ gases might not be able to escape. Because the pressure is low (fed from tank in loft) this "bubble" can't be shifted. These days "plumbers" (as they call thmselves) don't realise that on low pressure sytems the pipe works has to be installed without high points, the air/gases has to be able to escape throught the tap or back up to the vent (the one that curls over your tank in the loft.)

The problem is you have employed wanker in the past who has buggered up your system, it will need to be rectified for a permanent solution.

BTW, you don't need the Hoover. You need a short bit of hose to connect the hot & cold taps. Open hot tap & then cold tap. Close in reverse order. You might need assistant to hold the hoses in place. Run for half a minute or so.This will push any air/gases out far more thoroughly. Adhere closely to above instructions or you will get wet!

I like harrys solution as it is easy and you can do it yourself, If this works, even if you have to do every few weeks for a couple of months then you can look for a permanent solution knowing what the cause is.

[CJC]

Thanks for the response.

The only thing is, would the new boiler system change much of the previous pipe work that worked for the previous system?

As far as I remember they change a little of the configuration of the pipes in the airing cupboard to allow for the pump and controllers to be placed conveniently but apart from that I think the pipe work would have been the same.

Would getting a better pump resolve the gas bubble issue or is it something that I am just going to have to sort out with the hose?

I would love to rectify it fully but stupidly the house has just finished being decorated and I'd hate to pull up all the floors to put in new pipes etc.

In the mean time I am off to buy a hose.

Thanks

[Tabby]

Something doesn't look right about what's been said so far. You say the cylinder's upstairs, yet an airlock is blocking water flow. Those

2 statements look fairly incompatible to me, if you've got that much head, no matter how much air gets in there it'll simply get blasted out by the water.

I suspect the issue may be this: The header tank feeding the HW cylinder has a fill valve that isnt filling as fast as you're using water, so eventually the header runs dry, air enters the cylinder, and you lose head. This would explain the reduction of water flow and the air appearing. In the end I can only guess though, having not seen the system and not fully knowing its layout, or even type.

NT

[John Rumm]

Yup, this sounds more plausible to me as well... You would normally expect to get the problem after drawing off lots of hot water.

If it is this, then fitting a better float valve in the main cistern, or for that matter fitting a second one ought to fix it, and its not to disruptive to do either.

[CJC]

Talking to local plumbing shop today. He also mentioned something very similar to this. This had prompted me to take a look in the loft and I have two tanks up there. One larger than the other. Please ignore my ignorance but I sensed one must be for cold water and one for hot? Someone had mentioned to me it could be possible that one of these tanks are no longer in use which I am unsure. Unfortunately it is really hard to look too much myself as they are in an eve with restricted access.

However, whilst looking at the tanks I notice there are two brass taps between the tanks are these the fill valves. Is there a danger of changing them too much?

[John Rumm]

If they are in an area of restricted headroom, it might be the case that this limited the total tank size and hence two were installed. If they were joined by a large diameter pipe at a low level then they would function as one.

(needless to say that tanks in the eves are not well placed to deliver the best pressure - high up on studwork on an gable wall works better in this respect).

The float valve will be fed by the cold rising main (often in 15mm copper pipe)- it will go into the top edge of the tank at one end usually)

[chris French]

We can get airlocks in our upstairs paperwork (because of bad previous installation). standard, indirect HW tank upstairs, with cistern in the loft. Pipework from the cylinder to the bathroom duns a fairly long distance, up into the roof space, when it gets to the bathroom, there ar pipes going down to the shower, handbasin, WC and bath, the one to bath runs down, along a bit and then up to the bath taps. AFAIK, this has all or at least mostly been plumbed in 15mm.

HW flow to the bath is a bit ropey anyway, regularly get a bit of spluttering etc. If however someone turns on the shower/tap/flushes the loo when running a bath then normally it causes an airlock in the HW pipe. Which generally doesn't clear itself, leastways not for a few days at least. (can't even use the hose trick as the taps are all mixers, easiest way is normally to open handbasin tap and put hand over the end to force CW up the hot pipe that way)

I've never really managed to work out the mechanics of this, why drawing off the CW say by flushing the toilet should cause an airlock in the HW? It doesn't happen that often, now only if someone forgets, I'd do some replumbing, but the bathrooms planned to go this year hopefully anyway.

Yup, this sounds like a possible explanation

[Weatherlawyer]

Presumably there is no stop c*ck in the way? An old system then.

I have the same problem almost a trickle to fill the bath and bloody knocking when I use any tap, cold ones too.

When I move out I am going to write a long list of stuff the landlord expects me to do at my initial expense then get just a reimburement for the materials. Then I am going to give it to my neighbours and tell them to pass it on to the next unfortunate.

And write a not to myself not to get caught like that again. Notr tell anyone that i am a carpenter. For some reason that translates as plumber / dick head with some people.

[Tim Downie]

It's possible that you have a partial blockage on the outlet side of your hot water header tank. It could be something as simple as a gate valve that's not fully open or it could be that the pipe is internally corroded (if it's not copper) or some sludge/crud/dead bird has fallen to the bottom of your tank and is partially blocking the outlet.

When this happen, drawing water from the hot tank pulls air into the system via the expansion pipe (which usually curves over the top of the header tank in the loft.

Got a camera? A few pictures would help.

Tim