Central heating tank over-filling from somewhere!!!

podge3

My central heating is giving me more trouble :mad:

To make a long story short, I have discovered that my header tank is over-filling. There is a constant drip from the over-flow pipe on the soffit.

The puzzling thing is its not coming from the ballcock . I have tested this and I'm sure its not leaking. My only other theory is that the coil in the hot water cylinder has a leak and the water from the storage tank and header tank are mixing.

Any other ideas?

Outkast_IRE

ah problem solving i love this .

So you have ruled out the ballcock for sure ? i have seen situations where the ballcock only let in extra water in the middle of the night when the water pressure in the mains shot up higher . House owner would wake in middle of night to water coming out of overflow .

If its not that then yes the only other place extra water can come in from is the cylinder , a pinhole in the coil sounds like the culprit.

Is your cold water supply tank (big tank in attic) how is that situated in relation to the small tank .

In some setups they are both just in the attic at joist level on planks of wood. In other set ups the small tank is over the big tank . ?

Joey the lips

Have you one or two tanks in your attic. Which tank is the water over flowing in.

ART6

Does it happen all the time or only when the heating is on? If the latter, it's worth checking the vent pipe over the tank. Might be possible the system has a lot of air in it, so when the heating is on the air expands and forces some water out of the vent. Heating off, rads cool down, air volume reduces, make up water drawn in. Venting the rads might cure it?

podge3

Thanks for the replies, lads. To answer your questions:

- I have 2 tanks and the water is over-flowing in the central heating header tank.
- Both tanks are in the attic at the same level. Obviously the CH tank is smaller so the water level is below that of the storage tank.
- It is overflowing all the time - hot or cold.


I'm going to do some tests over the next few nights turning off the water and draining the tanks etc.

Outkast_IRE

sounds like the coil alright.

Joey the lips

Outkast_IRE wrote: »

sounds like the coil alright.

Do you think? The only way it could be the coil is if its traveling up the expansion pipe and the expansion pipe is fed into the heating tank. This is 1. Unlikely and 2 . He would hear the noise.

I imagine its the ball cock

However if the heating tank is actually lower that the main tank then the water could be traveling up the expansion into the main tank and traveling up the overflow for the heating tank.

If this all makes sense

podge3

Joey the lips wrote: »

Do you think? The only way it could be the coil is if its traveling up the expansion pipe and the expansion pipe is fed into the heating tank. This is 1. Unlikely and 2 . He would hear the noise.

Does it not all come back to water finding its own level? i.e. if there is a small leak in the coil then both water systems are linked and the water level will try and equalise in both tanks?

Outkast_IRE

Joey the lips wrote: »

Do you think? The only way it could be the coil is if its traveling up the expansion pipe and the expansion pipe is fed into the heating tank. This is 1. Unlikely and 2 . He would hear the noise.

I imagine its the ball cock

However if the heating tank is actually lower that the main tank then the water could be traveling up the expansion into the main tank and traveling up the overflow for the heating tank.

If this all makes sense

I said in a earlier post here ballcock leaving in at night or somethin like that but

your way are you trying to say the same as this?
lets say the Large tank and small tank are both just sitting on the joists on planks or whatever.
Water level in the large tank is higher than in the small tank .
Pinhole in coil , water will try and reach common level .
As large tank has a higher level it will win over its head of pressure being more , and force a small amount through pinhole attempting to find that common level .
It will find this common level as the cold feed pipe will leave it

Joey the lips

Outkast_IRE wrote: »

I said in a earlier post here ballcock leaving in at night or somethin like that but

your way are you trying to say the same as this?
lets say the Large tank and small tank are both just sitting on the joists on planks or whatever.
Water level in the large tank is higher than in the small tank .
Pinhole in coil , water will try and reach common level .
As large tank has a higher level it will win over its head of pressure being more , and force a small amount through pinhole attempting to find that common level .
It will find this common level as the cold feed pipe will leave it

Water level in both tanks will have to be the exact same. This is the reason you cannot set the 2 tanks on the same joist and if you do the small tank will overflow constantly. But its all very interesting. Pinhole seems obvious. The water in the main tank should be discoloured dont you think?

Outkast_IRE

Joey the lips wrote: »

Water level in both tanks will have to be the exact same. This is the reason you cannot set the 2 tanks on the same joist and if you do the small tank will overflow constantly. But its all very interesting. Pinhole seems obvious. The water in the main tank should be discoloured dont you think?

Iv seen you around the boards joey are you a plumber just out of intrest iv seen you give sound advice a good few times ?

The two tanks do not have to be at the same level they are two completely seperate systems . The water level in the big tank in no way should affect the level of the small tank if the system is correctly installed .
Its like having a full bottle of water and a half full one next to it . One doesnt affect the level of the other if things are working correctly .

The only place these two systems come into direct contact is the coil , even then the coil is basically a heating pipe that just runs through the cylinder . At no stage do the two seperate system waters mix.

The water in the main tank might not suffer from discolouration as its got a higher head of pressure(if both tanks are just sitting on joists) therefore the water will mostly go the one way . Unless the circulation pump forces some heating water into cylinder which can happen.
If discouloration were to occur the most likely spot would be through a hot tap . as the cylinder would be the problem area.

Joey the lips

Outkast_IRE wrote: »

Iv seen you around the boards joey are you a plumber just out of intrest iv seen you give sound advice a good few times ?

The two tanks do not have to be at the same level they are two completely seperate systems . The water level in the big tank in no way should affect the level of the small tank if the system is correctly installed .
Its like having a full bottle of water and a half full one next to it . One doesnt affect the level of the other if things are working correctly .

The only place these two systems come into direct contact is the coil , even then the coil is basically a heating pipe that just runs through the cylinder . At no stage do the two seperate system waters mix.

The water in the main tank might not suffer from discolouration as its got a higher head of pressure(if both tanks are just sitting on joists) therefore the water will mostly go the one way . Unless the circulation pump forces some heating water into cylinder which can happen.
If discouloration were to occur the most likely spot would be through a hot tap . as the cylinder would be the problem area.

So the solution is a temp by-pass of the coil to test this theory . It kinda makes you wonder. A new cylinder costs around 70 Euro. A call out costs 50.and an hour to bypass 25. It seems the op will figure all if nothing can be identified in the attic when up there. It seems for 300 Euro it will be easier to assume the coil.

Rather than test the theory I think most plumbers will just replace the cylinder.It seems an easier spent 300 Euro. The strange thing is if its not the cylinder the customer will never know.

I think to see the problem is the only way to know.

Outkast_IRE

Joey the lips wrote: »

So the solution is a temp by-pass of the coil to test this theory . It kinda makes you wonder. A new cylinder costs around 70 Euro. A call out costs 50.and an hour to bypass 25. It seems the op will figure all if nothing can be identified in the attic when up there. It seems for 300 Euro it will be easier to assume the coil.

Rather than test the theory I think most plumbers will just replace the cylinder.It seems an easier spent 300 Euro. The strange thing is if its not the cylinder the customer will never know.

I think to see the problem is the only way to know.

I agree this problem will be identified in the attic , we were just establishing the alternative i go with simpliest explanation first which is ballcock
after that its cylinder . i dont think there is a 3rd option here unless new info comes up

podge3

Thanks for the input lads.

Last night I tied up the ballcock in the cold water storage tank and drained it so that the level was below the CH tank. When I checked this morning the CH level has not risen at all and had in fact dropped slightly - probably due to the water cooling overnight, or maybe a small drain back into the cylinder?

So it looks like its definitely the coil is the problem. I will bypass it at the weekend and see if that cures the problem.

@ Joey the lips - is a cylinder only €70? I'll replace it myself rather than get a plumber to do it.

Joey the lips

podge3 wrote: »

Thanks for the input lads.

Last night I tied up the ballcock in the cold water storage tank and drained it so that the level was below the CH tank. When I checked this morning the CH level has not risen at all and had in fact dropped slightly - probably due to the water cooling overnight, or maybe a small drain back into the cylinder?

So it looks like its definitely the coil is the problem. I will bypass it at the weekend and see if that cures the problem.

@ Joey the lips - is a cylinder only €70? I'll replace it myself rather than get a plumber to do it.

chadwicks + vat. consider increasing to a 42" if you are confident in doing it

podge3

Joey the lips wrote: »

chadwicks + vat. consider increasing to a 42" if you are confident in doing it

I dunno what size the current one is but space is a bit tight so I think I'll just replace like with like.

On a slightly different note, can you get unlagged cylinders anymore?. I would much rather a bare copper unit that I can strap a lagging jacket onto. You really have no idea how much water is in the ones that come pre-lagged whereas you can put your hand inside the loose jackets and check how much HW you have.

Joey the lips

podge3 wrote: »

I dunno what size the current one is but space is a bit tight so I think I'll just replace like with like.

On a slightly different note, can you get unlagged cylinders anymore?. I would much rather a bare copper unit that I can strap a lagging jacket onto. You really have no idea how much water is in the ones that come pre-lagged whereas you can put your hand inside the loose jackets and check how much HW you have.

Yes you can. If chadwicks dont have them pm me and I will give you a number of someone who does. Although its priced in ltr/gallons if you measure the high and width to the nearest inch the people on the sales counter will know. The standard varied between 30 x 15 and 36 x 18 most people have a 36 x 18 now. Fit the immersion before you fit the cylider. Makes life a little easier.

browner85

good luck with gettin a cylinder for €70 euro.... and u would want to know what your at before tryin to change it urself!!!

wee bey

Don't think 70euro will get ya a cylinder buddy. And don't attempt to change the cylinder unless your confident. It's not a simple DIY job.;)

Micky Dolenz

Just to add my bit to it, it can only be the coil in cylinder.

Changing it will take a good plumber about 3 hours, don't attempt it yourself unless you are a plumber. Draining down system and disconnecting the old cylinder is the easy part. You will have gate valves that will let by, you will have a pain swapping over immersion, so spend the €35 and get a new one.

wee bey

Yep he's spot on there. I'm a plumber myself and have changed 3 old cylinders in last week and nothing too straightforward about it. Old valves may be passing or may not re-open. Filling the heating system can be a headache. If an immersion fitted it will have to be re wired etc etc all in all its safer get a pro I'm afraid.

Outkast_IRE

agree i would get a pro and the new cylinder even though the same size the pipwork may not match up exactly .

Also consider getting the pre insulated cylinder and maybe get a cylinder thermostat and motorized valve , honestly the preinsulated tanks are brilliant for holding onto heat i can heat a cylinder of hot water now and if i dont use it i am confident it will still be at a very warm temp tommorow no bother. i wouldnt reccomend the un insulated type to anyone . Combine the insulated one and proper controls = this job being well worth it and will pay for itself .

podge3

Once again, thanks for all the help lads.

I have now bypassed the coil and the over-filling has stopped so a new cylinder is required.

I'm going to change it myself. I'm handy enough with the spanners and have installed sinks, radiators, motorised valves etc over the years. There are only 4 connections on the tank itself so shouldn't really be a problem (hopefully ).

I have priced a tank in my nearest builders providers - €150 :eek:. Looks like I need to shop around a bit.

podge3

Update on this...

I changed the tank yesterday. Quite a handy job really but you would need to have some DIY plumbing experience.

It took about 4 hours but most of this was "draining" time. I had a problem getting a good seal on one of the joints and had to drain the tank several times, which seemed to take forever. The connections on the new tank were in the exact same position as the old ones so it was just "plug'n'play".

The new tank cost €120 plus another €20 or so for various bits. I also changed the immersion as a new one was only €28. I got an unlagged tank because

1. I could never tell how much hotwater was in the old pre-lagged unit. I intend getting a lagging jacket ASAP but you can put your hand inside the jacket and check for heat.
2. The plumbers suppliers didn't have the pre-lagged type

I have to say the new tank is a piece of crap. Its wafer thin and I picked it up with my finger. The plumbing guy said all new tanks are like this and that the lifespan of modern tanks is only about 10 years.

So thanks again for all the advice lads.

P.S. I found a kitchen knife inside the old tank

Joey the lips

Well done. Sorry about the price. But very good work