Overflow Problem

[Homewrecker]

Morning all

This is really bugging me:

We have a gravity fed system in the house with the cold water tank in the loft to feed the HW cylinder. Just recently this has started to overflow intermittently but quite a large overflow. I've checked the inlet valve and I'm convinced that it is nothing to do with this. I think it could be the expansion pipe from the cylinder to the tank causing it. Could someone give me any ideas on:

1. How I can confirm that it is this
2. What the causes could be
3. Remedies

Let me know if I need to give more info.

Thanks in advance

Chris

 

[ChrisR]

Is your C Heating header tank higher than the CW one? If so the coil in the HW cylinder could be leaking between the two. Don't clean your teeth with it!

Turn off supplies to both and check levels overnight. Complication is that the CH level will rise as water expands on heating.

 

[kevplumb]

We have a gravity fed system in the house with the cold water tank in the loft to feed the HW cylinder

sounds like a primatic

do you have one tank or two

 

[CopperCylinderMan]

Are your cold taps mains fed?

Does the overflow happen when you use a particular appliance eg washing machine? Thermostatic mixing shower?

It 'could' be crossflow - mains cold getting into the hot system.

 

[Homewrecker]

Thanks for the replies so far.

To answer all questions:

1. Two tanks in the loft
- Cold Water Tank fed fom the mains supplying the cylinder
- CH Filler Tank fed from the mains
The CH filler tank level is lower than CW Tank Level (its a much
smaller tank) - will that rule out the CH Coil leaking into the HW
Cylinder

2. All cold water taps are fed from the mains - will this rule anything out?

3. Because its intermittent I've not been able to associate it
with any particular thing. We did have the CH on last night for a bit
but I'm sure the last time it happened we didn't.

I wondered if it might be:

1. Cylinder Thermo dodgy
2. The Diverter valve is dodgy and when the CH is on we're also
heating up the water