Water constantly flowing through tundish

todolist

I have an unvented hot water cylinder.There is water constantly flowing through the tundish.I was told this could be solved by opening the Temperature pressure relief valve.I don't know which valve that is.I've attached some photos of the system I have.Any advice would be really appreciated.

dathi

todolist wrote: »

I have an unvented hot water cylinder.There is water constantly flowing through the tundish.I was told this could be solved by opening the Temperature pressure relief valve.I don't know which valve that is.I've attached some photos of the system I have.Any advice would be really appreciated.

the pressure relief valve is the red one beside the blue sticker at top of cylinder. its the one which is opening due to a build up of pressure in your cylinder and releasing water to the tundish . you need someone to check the pressure vessel to see has it lost its air pressure (small white tank beside cylinder)

todolist

dathi wrote: »

the pressure relief valve is the red one beside the blue sticker at top of cylinder. its the one which is opening due to a build up of pressure in your cylinder and releasing water to the tundish . you need someone to check the pressure vessel to see has it lost its air pressure (small white tank beside cylinder)

Could opening the temperature pressure relief valve solve the problem without having to get expansion vessel checked.If there is a problem with the expansion vessel how would that effect the system?

corkgsxr

I would say if it's constantly running then it's actually a problem with the pressure reducing valve.

K.Flyer

todolist wrote: »

Could opening the temperature pressure relief valve solve the problem without having to get expansion vessel checked.

Short answer is No.
Water passing through the tundish is a symptom of one or possibly more than one problem.

If there is a problem with the expansion vessel how would that effect the system?

As the water heats up inside the tank the pressure inside the tank increases. Instead of this increase in pressure putting additional stress on the components, the expansion vessel absorbs the pressure increase.
You need to call someone who is familiar with installing and servicing un-vented hot water cylinders and who can determine where the fault(s) are and carry out the appropriate repairs.

todolist

K.Flyer wrote: »

"Water passing through the tundish is a symptom of one or possibly more than one problem"

So opening the TPRV could solve the problem.Isn't it worth trying that before having to get a plumber?

K.Flyer

todolist wrote: »

So opening the TPRV could solve the problem.Isn't it worth trying that before having to get a plumber?

No, it will not solve the problem.
The TPRV is a safety device fitted to relieve excess pressure or excess temperature that has build up due to a malfunction of another component or the TPRV itself is faulty.
If you are not familiar with these things it is best to get someone in who is. Randomly opening the valve may cause greater problems for you than you have already as it may not close fully again and you could have a torrent of water that you cannot stop.
These items are NOT DIY'er stuff and need to be attended to by people who know what they are dealing with.

todolist

What do you think of this?
https://youtu.be/DFufKEIvbTo

K.Flyer

todolist wrote: »

What do you think of this?
https://youtu.be/DFufKEIvbTo

He is working on a Megaflow Unvented Cylinder which has an internal air gap and no external expansion vessel. Yours is not a Megaflow and has an external expansion vessel, a very different set up.
It's not a very good idea to drain any system via the PRV as this can allow debris to get lodged where the seal is and it will not allow it to close properly.
Now using your video for reference, at approx 1m20s he says that the method he describes is for the Megaflow Unvented Cylinder, and at 1.23 he emphasises how you should leave the rest of the components to trained experienced people.
As he says at 1.30..
"...if you do not know what you are doing, do not mess about with unvented cylinders..."

todolist

K.Flyer wrote: »

He is working on a Megaflow Unvented Cylinder which has an internal air gap and no external expansion vessel. Yours is not a Megaflow and has an external expansion vessel, a very different set up.
It's not a very good idea to drain any system via the PRV as this can allow debris to get lodged where the seal is and it will not allow it to close properly.
Now using your video for reference, at approx 1m20s he says that the method he describes is for the Megaflow Unvented Cylinder, and at 1.23 he emphasises how you should leave the rest of the components to trained experienced people.
As he says at 1.30..
"...if you do not know what you are doing, do not mess about with unvented cylinders..."

I thought all unvented cylinders have an expansion vessel either internally or externally? Mine just happens to be external.The plumber in the video suggests this job is the only one an unqualified person could do themselves.Whaddy think?

K.Flyer

todolist wrote: »

I thought all unvented cylinders have an expansion vessel either internally or externally? Mine just happens to be external.The plumber in the video suggests this job is the only one an unqualified person could do themselves.Whaddy think?

I am not going to advise you any differently than before, if that's what you are hoping.
Water passing through a PRV is a symptom of a problem somewhere. Unless you know how to diagnose and rectify the issue you should leave it alone and get someone who is familiar with unvented cylinders.

That's what I think.