Header tank in Loft constantly over flowing sice having bathroom renovated

[scotjan]

Bathroom is downstairs
Cold water supply is straight from mains
Hot water is from tank
Header tank in loft
Expansion tank in loft
Heating system is vented gravity
Hot water is kept in cylinder in bedroom below the loft tanks
Hot water supply is very good pressure
Heating system has now been power flushed and is working normally – heating up rads much quicker
Hot water seems to be normal ie have hot water

· Previous installation which had no problems

Bathroom

Mixer tap for bath/shower
Two taps for sink

· Current installation

Mixer tap for bath – pressure for hot water and cold water very good
Thermostatic shower – not pumped- pressure is good. Although sometimes the shower runs for about 45 seconds and no water comes out. Then it’s ok
Mixer tap for sink- cold water pressure very good still. Strangely now the hot water trickles out , but I have been advised that the taps may be for mains pressure only.

· Problems now are

Water going into the big header tank in loft and over flowing consatntly.
Can be alleviated temporarily by running hot tap
Water filling up the tank even when the heating or hot water is not on.
Vent pipe above cylinder is full of water? Thought it should be for air vent?
Haven’t yet investigated where exactly the water is coming from to fill up the tank. Having said that when you run the hot tap you can hear the water refilling the tank. But when it is over flowing I can't hear any water running.
can hear water trickling in pipes around the cylinder and I never heard that before.
Contractor's suggestion is that it is due to low hot water pressure and the mixer tap is forcing the cold water back up to the hot water supply. That I need a combination boiler to address the low hot water pressure issue. But I didn’t have low hot water pressure before and still don’t except that one mixer tap.

An independent plumber suggested that I may have a leaking coil in the hot water cylinder and that I would need a new cylinder.
Or could it be an air lock?
Did have a massive air lock in central heating after work was completed but that is sorted now.

I'm so confused and don't know what to do

 

[Phil]

Interesting.........

If everything was okay before you had your bathroom done then I would be looking at the new mixertap as a culprit, although the cold would only backfill the hot pipework when the tap is open and mixing hot & cold together so something sounds wrong there unless he's somehow cross connected the pipes?

Did the installer fit a one way valve on the hot feed on the mixertap?

If not fit one of the low pressure swing valves in the link, I use them all the time when fitting mixertaps on unbalanced feeds because on the kind of mixertap you've got the hot & cold mix inside the tap, the other (better) kind is the mix in the bowl type where the hot & cold are kept seperate untill they exit the spout.

The cold finds its way down the hot pipe and into the cylinder, then it goes back up the cylinder feed pipe and into the bottom of the tank. The water level in the vent pipe is always the same level as the water in the tank (water finds its own level).

So in your system the ways that can cause the CWS tank to overflow are:

Ballvalve

Pin hole in cylinder coil

Cold passing into hot on mixer tap, shower valve, washing machine etc.

Check Valves & Strainers & Drain Cocks

 

[scotjan]

Hi Phil

I don't think a one way valve was fitted to the hot pipe. The pipes are all in a unit now but all I can see is one of those bendy pipes with an isoloating switch. I haven't been using the tap as a mixer because of the different pressures. I can remember years ago having to get rid of air in the pipes by the hose pipe on the cold feed to the hot so I thought the mixer might be having the same effect.

Wonder if it could be the shower that is causing the problem then. Although it does get very hot and the pressure seems ok. One of my work colleagues asked me if it was the type you can use for mains pressure as well as tank pressure. I have no idea but if it isn't then I suppose that could be the culprit. Then in that case surely they shouldn't have installed it?

How can I check to see if it's the shower or the tap
Can I check the cylinder coil somehow

 

[Phil]

Does the tank filling/overflowing happen constantly?

To test shower/mixertaps turn on to full hot untill the hot pipe is hot and then turn the heat down and allow cold to come in, the pipe will go quickly cold if its back filling the hot, you will also 'feel' the cold going down.

You could also use the isolators under the tap and see if the problem stops, roll your sleeve up and try to block the 22mm outlet to the cylinder at the bottom of the CWS tank, infact do that first to confirm mains water is coming out of there if it is you wont be able to hold your finger over it for long.

Presuming the taps/shower aren't faulty, the above would only happen when the tap is being used and in the 'middle' setting.

Just re read you post, it seems you have normal basin taps on the bathroom basin and on the bath you have a mixertap bath filler with a shower fitting?

If yes then remove the bath panel if posible and isolate the taps and see if that tank outlet stops.

Could be a pin hole leak in the coil but more likely to be connected to the new bathroom refurb.

 

[scotjan]

Hi Phil

yes water is running constantly, only thing that stops it is running the hot tap for a while then it takes quite a while for it to start again.

Bath taps are mixer but both have really strong pressure. Sink taps are mixer where they used to be separate. Sink tap now has really bad pressure on hot water but normal for cold water.

Thermostatic shower was fitted at the same time which gets realy hot. A a result we have to use it in the middle setting.
Would have to remove bath panel to get to pipe work and hopefully they put isolation taps on the shower pipes. I did see isolation pipes for teh bath taps before they put panel up.

As for putting my arm in the cold tank, I'm actually femail and its covered in spider webs🙂 So maybe I'll get someone else to do that.

 

[Phil]

Where are you Scotjan?

If you're anywhere near me I'd pop over for a free diagnosis.

 

[scotjan]

sadly I'm in Watford in Herts. I guess what I need is a local plumber to give me an assessment.

Strangely yesterday after using the washing machine the over flow stopped. The washing machine is on the other side of the wall to the shower. The overflow didn't restart again all night and this morning when I put the shower on there was delay of about 40 seconds until the water came out. I'm guessing now that there was no water in the shower pipes and that is why there was no over flow because the hot and cold were not mixing.
But I have no idea really and I don't know what to do for the best. The contractors deny anything and all they say is install a combination boiler and it will sort out the difference in pressure. They won't admit it was anything to do with them and I need to prove somehow that it was.

 

[Phil]

40 seconds is a long time, there's something wrong somewhere.

If there's no water in the pipes there must be air, next time you turn the shower on immerse the showerhead in a bucket of water first and see if any bubbles come out.

This 'independant plumber' did he ever come to your house?

Whoever you get it is important you tell him you've just had the bathroom done so he's not barking up the wrong tree.

It could be the mixertap on the wash hand basin, there are ways to test like turning mixer to full hot and let the pipe at the back get hot and then turn it to mix with cold and feel if the hot pipe immediatly goes cold. As said it would only normaly do this when you're using the tap.

Who fitted the bathroom? These companies really do like making sure you wont ever recommend them, ................"to solve the problem simply fit a combi"

Jokers!! 🙄
Do you have a water meter? If so don't use any taps and appliances and see if the meter moves when its overflowing.

 

[scotjan]

Thanks Phil for all your advice you have been so helpful.
I'll try the mixer tap when I get home later. I just hope it isn't the thermostatic shower they fitted as all the pipes are in the wall.

I will name and shame if it is down to them don't worry and if they won't fix it I guess it will hav to be a small claims court next. Don't need the hassle but won't let them get away with it either.

I'll let you know what the plumber finds and fingers crossed it's only an air lock

 

[Winston]

I think its the shower, the cold water pressure from the main to the shower is pushing back through the hot water pipe to the cylinder then going to the cold water storage tank. If you listen carefully can you hear water. is the hot water pipe very cold when not in use?

If my diagnosis is correct fitting a non return valve to the hot would rectify this though I am suprised you are getting a good shower as it is ideal for both supplies to be of equal pressure, another way would also be to put a pressure reducing valve onto the cold supply for the shower.

I hope what I have said makes sence and let us know how you have got on.

 

[scotjan]

Funnily enough I have had my ear glued to the shower taps to try and hear water but couldn't. trouble is the pipes have been put into the wall and tiled over. Ijust hope that when the chrome plate is taken off then it will give access to put a valve on otherwise the tile swill have to come back off.

I will definitely let you know the outcome.

Not much contct with the internet next week as I'm on a course for work so if you and Phil don't hear fro me that is the reason why.

Thanks to you both for taking the time to help.

 

[scotjan]

Hi Phil

Sorry it's been 2 weeks but I was on a residential course.
Came home to find the overflow is now intermittent but then I did turn the mains cold pressure down before I went.

It still overflows but its hard to pinpoint exactly the cause.
I have one idea though which may or may not make sense.
If the overflow is not running and you go to use the shower then you often find that it takes 45 seconds for any water to come out.
When it is overflowing there is no delay from the shower.
And it sometimes stops when I use the washing machine which is on the otherside of the wall. I mean it stops even after the tank has refilled.
I assume that the feed for the washing machine is the same as that for the shower. Could this be the cause of the water not being in the shower immediately.

I have called the original plumbers today and have told them that they need to sort out the issue. their response was that it is caused by uneven water pressure. I then expalined that they fitted the taps and shower and as they knew the cold was mains and hot gravity, if it wasn't suitable to have a mixer tap or thermostatic shower then they should not have fitted it. They are going to get back to me but I'm not holding my breath.

Well we'll see what happens now

 

[vanjanflo]

i am wondering how you got on? i have a very simular problem if you see my thread on valves and taps called "mixer tap hell" - got a good answer on there from a senior member - let me know either way as i am keen to hear how you got it sorted with the plumbers who caused it to go wrong.

 

[WHPES]

Sounds like you've been done by a cowboy too.

The cold feed for a mixer shower should come from the tank in the loft the same as the hot feed and NOT from the rising main. Another topic currently on with the same symptoms and same problem.

 

[scotjan]

i am wondering how you got on? i have a very simular problem if you see my thread on valves and taps called "mixer tap hell" - got a good answer on there from a senior member - let me know either way as i am keen to hear how you got it sorted with the plumbers who caused it to go wrong.

Well strangely it seldom happens now. But it did start agin this week having not done it for 2 months. To be fair the plumbers came back and said they could turn down the pressure for the cold water at the shower itslef but that would result in hardly any water flowing so we left it as it was ok.
I have no idea what suddenly caused it to start again but it is definitely the shower that is causing it. It has been going for three days now. All they say is get a combi boiler🙂 I don't want a combi and anyway thats because they think they will get the job to install.

 

[traineedrip]

Hope you get it sorted soon. Is it still taking 45 secs for the shower to flow? Did you try putting it in the bucket?
Id be interested to know if theres air in the pipes or if the showers holding it back?

 

[vanjanflo]

All they say is get a combi boiler🙂 I don't want a combi and anyway thats because they think they will get the job to install.

co-incidentally all my "plumber" kept saying was you need to upgrade your system to a combi/high pressurised system... i now know why he kept saying that - because this would put right his wrongs!
WHPES response to my post (mixer tap hell) helped unravel our problem, (which sounds very simular to yours) our bathroom re-fitter/ "plumber"
has connected my shower/bath mixer to the rising main when it should be connected to the CW tank in the loft... hence the unbalanced pressure and spurting overflow of hot water going up into the cold header tank... is this what your plumbers have done per chance?

 

[Billy Bob Bob]

co-incidentally all my "plumber" kept saying was you need to upgrade your system to a combi/high pressurised system... i now know why he kept saying that - because this would put right his wrongs!
WHPES response to my post (mixer tap hell) helped unravel our problem, (which sounds very simular to yours) our bathroom re-fitter/ "plumber"
has connected my shower/bath mixer to the rising main when it should be connected to the CW tank in the loft... hence the unbalanced pressure and spurting overflow of hot water going up into the cold header tank... is this what your plumbers have done per chance?

probably,total balls up!you can do this on certain showers with a injector/flow limiter also a pressure reducing valve needed,your plumber is taking the p@@s,you can have uneven pressures if you buy the right kit and install it proply

 

[scotjan]

I have read since installation that the cold supply should be connected to the cold water tank in the loft and not the mains. My bathroom is downstairs so it is going to be a big job I fear. But before the shower was fitted I did have a shower/bath mixer tap and had no problems unless you ran the hot water for a bath a full pressure. It would then run cold, almost as if it was bypassing the hot water supply. There would be a whole tank of hot water but only cold water coming out of the hot tap. Used to spurt a lot then go cold, really annoying.

I haven't checked the delay in water coming through by putting the shower head in a bucket because it happens so randomly and is still very intermittent. Having said that when the water is over flowing there is no delay.

 

[WHPES]

There may still be the original pipe for the cold coming from the header tank capped off under the bath somewhere.

 

[scotjan]

ok thanks. That is something worth investigating; hadn't occured to me that might be there

 

[vanjanflo]

WHPES i would appreciate your opinion- the cowboy plumber fitted one way valves to both hot and cold pipes (i'm told only need them on the cold) but anyway he fitted them to the bath/shower mixer and the basin mixer in the new bathroom in a bid to stop the hot water going up into the CWH tank causing overflow problems etc, but since he has done that the problem with the overflow still happens on and off - when nobody is using any water! and only stops when we isolate the water supply to our other shower - which is situated downstairs. incidentally this groundfloor shower has a pressure reducing valve on it, & is also connected to the rising main but as it is situated downstairs the balance seems to be fine and the shower has always been very good and no problems with temperature control.
cowboy sent a plumber mate round hoping to just get away with putting pressure reducing valves on everything but i haven't let him do this as it feels like more bodging.
can you tell me how the problem has shifted from the new bathroom to the groundfloor one? and what is the solution/remedy for putting it right

 

[WHPES]

For a start, check valves aren't for rectifying design faults.

The balance won't be fine. The mains pressure will vary throughout the day, usually greater in evening when less demand.

Wherever you have a nixer with an unbalanced supply you are going to get problems.

The only way you're going to fix it is to have pressures exactly balanced i.e. plumb the cold in from the header tank.

You could use shower valves for unbalanced systems but you could spend a lot of money and effort and the end result be unsatisfactory.

You would only use PRVs where your shower is supplied from a combi or unvented.

 

[vanjanflo]

thanks for the answers.
this plumber mate of the "cowboy" was trying to tell me the problem cant belong to the new bathroom anymore since the first guy fitted one way valves. he was saying it just cant happen anymore with the valves in place so is a problem with my 3 yr old shower but never the less they were prepared to put valves everywhere!! it just doesnt add up my instinct tells me its bodging and might even cause more problems.

i have a feeling i may have to print this off to use in court so i take it you a registered plumber etc with the knowledge you have... just for "the record". thanks again WHPES.

 

[WHPES]

No, it can only come from a competent person who inspects the installation and sees it first hand. No good quoting any of us from here - on the forum we have only what you tell us. Where in the country are you? Perhaps one of us could inspect it for you? Don't even try printing this off as it will mean nothing without a physical inspection and report.

All being said it is common knowledge that hot and cold should originate from the same header tank. It's normally only with a combi where you may have unbalanced supply issues to address.

If you can find the installation instructions for the shower mixers (or at least obtain copies from the manufacturers) you will find the bit about requiring the pressures to be balanced. That would be the most useful document to find.