Recurring airlock? in hot water supply

[grekko]

Over the past 3 or 4 months I have noticed the hot water flow from the bathroom tap reduces daily until it becomes a trickle, the kitchen hot water tap also reduces flow but not the same extent. I am now regularly having to use the washing machine hose connection solution to clear the airlock(?). After applying this regular solution the flow in the bathroom and the kitchen appear to flow with similar pressure, but as days pass I begin to notice that the hot water bathroom pressure/flow is getting less(until eventually it stops flowing) and will almost stop if the kitchen tap is opened at the same time, either over sink or via washing machine or dishwasher. Is there a fairly easy solution or will this require major plumbing servicing.
I have a boiler that heats the water for the storage cylinder and central heating. (indirect?).

 

[SimonJohns]

This could be caused by a pipe under sizing. So it creates a slight vaccum when turning the tap on.

Try fitting some check valves before the outlets

 

[diamondgas]

If you have a blockage/restriction of flow in the feed pipe to the cylinder then these symptoms can occur. Is your hot water headder tank modern and proply covered and insulated? Any debris in the tank?

 

[Kev the gas]

Is the cold water tank filling up fast enough after running a bath?, causing an air lock.

 

[stevetheplumber]

as above id put a new ballvalve in the tank ,cheap and easy and most likley to cure the problem if its a undersized tank you could even put two ballvalves or a larger one to help it keep up

 

[grekko]

Thanks for all the advice guys but, no success, I'm back to square one. I replaced the ball valve on the tank and it appears to flow fine , well for a few days until the water flow becomes restricted once more, so when this happened I went to check the valve and it was still flowing into the the tank,although only for a short while until the hot water flow virtually stops.....I pushed the ball down to restart flow but still no hot water flowing....no debris going out through outlet so not muck from tank causing blockage...what now? Cylinder fills with hot water from boiler. Forgot to mention,I can temporarily clear the restricted flow if I connect the washing machine cold hose to hot supply and force it back....but only for 2 or 3 days until I get the problem back. P.I .T.A to be doing this each time.

 

[Paulus]

There should be a gate valve between the header tank and cylinder, have you checked to see if it's fully on. If it is, it may be faulty and not allowing water to flow into cylinder which would cause a vacuum.

 

[grekko]

Thanks for that Paulus, I must admit I haven't checked if it's faulty, probably because it refills the cylinder on a few days for enough pressure to enable the hot water flow, but as you say it may have some fault which prevents the water being able to create enough pressure as the days pass, I'll give it a check. Thanks for pointing it out.

 

[diamondgas]

grekko - Simple test to see if the cold feed supply/cylinder conections are restricted:

You'll need help to do this by-the-way

Get yourself a jug/glass of water. Get to your header tank and imerse the open vent pipe, the one looping over the top of the tank, into the jug/glass. Now shout down to whoever to turn a hot tap on, preferably the bath tap, and watch to see what happens to the water in the jug/glass. If the open vent pipe drinks all the contents you have a restriction... the water level may move a little but shouldn't be 'sucked' out!!!

 

[stevetheplumber]

just a thought is the main shared? could main flow to your tank be stopped by another flat stealing the water ? ive had this on 3 flats one main top flat got no supply to tank

 

[Paulus]

Thanks for that diamondgas, I'd never thought of that.

 

[diamondgas]

Thanks for that diamondgas, I'd never thought of that.

You're welcome

Old school trick Can be used on open c/h header tank too to check out that vent if you suspect air being drawn in.

 

[grekko]

Hello guys here I am back again but this time my problem has expanded.....not only do I still have the problem with the restricted hot water flow; and I've had a couple of plumbers/engineers look at it to no avail, they were as puzzled as me, I now have a further problem with the cold water supply tank repeatedly overflowing at the rear of the property. Sometimes it's fairly heavy, at other times barely a trickle. I notice it is heavier when the boiler is burning to supply the cylinder with hot water ,it reduces flow if I turn of the water heating, and at other times when the central heating is asking for heat it causes a similar overflow......is this a serious condition or one which can be easily traced and rectified....I'm not prepared at the moment to fork out on plumbers/engineers if they are going to return an answer similar to my earlier problem......please can someone help me save what few strands of hair I have left from being torn out in exasperation.

 

[Mike Jackson]

Is the CH header tank higher than the storage cistern? Could be a split coil in the cylinder.

 

[kozak1968]

Are there any filters in the tap spouts. They may be blocked causing poor flow rate.

 

[stevetheplumber]

which tank is overflowing?

 

[grekko]

which tank is overflowing?

Hi Mike,
It's the cold water supply tank for cylinder ,toilet etc, the smaller tank for the C/H is giving no cause for concern.

Sorry Steve,I read wrong post.

 

[grekko]

Thanks in advance to to everyone for their advice/help, here's the situation now:
I still have the overflowing water from the cold water supply tank, and I've had a new float valve fitted, but the tank is continuing to fill and overflow.......the water in the tank is almost tepid at times. What has become noticeable is that the overflow will still run , even if it's only a trickle, hours after both the C/H and Hot Water is switched off at the boiler......plus the hot water takes forever to get warm at the bathroom tap, much longer than previously.....there's also the problem of a reducing supply of hot water, it eventually runs to a trickle and I have to attach the washing machine hose to the hot tap to get a decent flow again (but that doesn't last for long after running the hot water).......had plumber/C/H engineer in and they are puzzled so you can imagine how worried I am becoming at this unsolveable? problem.......C'mon guys please please HELP!!!!!

 

[Dotty]

Your heating f&e tank is higher than the cold water storage tank, yes?

The ballvalve is constantly running in the f&e tank yes?

 

[grekko]

Your heating f&e tank is higher than the cold water storage tank, yes?

The ballvalve is constantly running in the f&e tank yes?

No to both
f&e tank on same level in loft and new ball valve as I stated fitted friday and working as it should., water is enterig cold water supply tank from the base of tank or at times from vent over tank.

 

[Rik]

Mixer tap or shower valve allowing mains pressure to push back up into tank maybe?

 

[grekko]

Mixer tap or shower valve allowing mains pressure to push back up into tank maybe?

Hi Rik,
shower is the electric/instant hot water type, but do have 2 monobloc taps....1 in Kitchen and 1 in bathroom......another thing I've discovered is that when I switch off the water heater on the boiler the overflow problem stops and yet the C/H runs fine.....any link maybe and if so what's the solution?

 

[glenno1]

Have you got a gate valve fitted,if so is it fitted vertically

 

[Davinder]

Where abouts do you live Grekko? Maybe someone for the forum can go have a look?

 

[stevetheplumber]

could be the stat on the boiler or immersion whichever your using to heat the tank

 

[grekko]

Could somebody,if my sketch is readable, explain what all the pipes are for, it looks a real heath robinson contraption:

 

[thompsonbrown]

when you clear air lock how long do you connect hose for

 

[WHPES]

Came across a similar problem a couple of years back. Traced it back to the remains of a dead mouse in the pipework.

 

[grekko]

It became unbearable today....the overflow started spewing water out onto the garden again,thinking the hot water had overheated maybe I went to check, NO, it was lukewarm.....went into loft no sign of water entering the cws tank....but full past the overflow. Went down and drained off all the warmish water till the ball cock was low enough to start refilling.......put boiler back on for hot water...3 hours later just warm again from tap but overflow spewing out again.....checked cylinder and it was a lot hotter than water out of taps.....I'm being driven nuts by this, and before anyone advises a plumber each time I've asked for help they each recommended changing ballcock...wouldn't entertain any other reason for overflowing, surely there's a decent plumber who's come across a similar problem....I'm not paying out for another useless ballcock. PLEASE PLEASE HELP.
I think I've added before the reason why I thought it was an airlock, but anyway when the hot water usually runs a trickle (aftr 2-3 days) I blow back cold from the mains into the hot tap for about 30 seconds and that gives temporary relief, but I need to know the fault and solution.

 

[WHPES]

You've got cold water getting into the hot system from a faulty mixer or even washing machine etc somewhere the way I see it.

 

[grekko]

You've got cold water getting into the hot system from a faulty mixer or even washing machine etc somewhere the way I see it.

What puzzles me is this....why should the hot water only run from kitchen/bathroom taps for a day or two until it slows to a trickle or stops if as you say cold water is getting to the hot system, wouldn't the water not get heated up as it usually has until today....cold water forced back up the hot pipe clears the trickle flow temporarily.....just curious.

 

[WHPES]

Dunno, really need someone to come and inspect it to know properly.

 

[Mike Jackson]

If the cistern is overflowing and the ball valve is fine water is getting back into the system some other way. The two most common things are a faulty coil in the hot water cylinder and a faulty mixing valve.

I've lost count of the number of times I've been called to jobs where "plumbers" have insisted that it must be the ball valve. You need someone with a bit of experience and common sense to have a look.

 

[plumb_know]

To see if it is cold mains water pushing back up the hot pipe work from a tap or appliance, see if a plumber can fit check valve on to hot water draw off from cylinder just after vent pipe, temporarily and see if this stops the overflowing problem. If it does then you know the overflowing is caused by mains being pushed back into tank. If it doesn't then you know to look at hot water cylinder. Another thing is have you had anything installed a month or so before you noticed this problem, if you have this could be source of problem. As for the blockage it may be caused from scale in cylinder. I noticed on your diagram you hot water pipe runs back into the loft? Is you cold water tank in loft raised to give good pressure or do you have negative head pump fitted? Hope some of this helps! Where you from as someone from the forum may be able to pop round and help, as its hard to solve a problem without being there.

 

[grekko]

To see if it is cold mains water pushing back up the hot pipe work from a tap or appliance, see if a plumber can fit check valve on to hot water draw off from cylinder just after vent pipe, temporarily and see if this stops the overflowing problem. If it does then you know the overflowing is caused by mains being pushed back into tank. If it doesn't then you know to look at hot water cylinder. Another thing is have you had anything installed a month or so before you noticed this problem, if you have this could be source of problem. As for the blockage it may be caused from scale in cylinder. I noticed on your diagram you hot water pipe runs back into the loft? Is you cold water tank in loft raised to give good pressure or do you have negative head pump fitted? Hope some of this helps! Where you from as someone from the forum may be able to pop round and help, as its hard to solve a problem without being there.

We're in the Liverpool area Plumb_know.

 

[gassafe]

Looking forward to hearing the how you got in with this Grekko!!!

I hate finding an old thread of interest, reading 3 pages and it all stops!!!