Oso unvented. Cold water through tundish

[armyash]

Had a customer ask me to look at her unvented cylinder.

Cold water running through tundish. Isolate supply to cylinder and the water stops running, needs new combi valve.

She did have insurance who refused to touch it because it hadn't been serviced for 2 years.

I've advised to change t and p valve and expansion valve also so all the components are new and saves something else going in the near future. Would you say that is good advice? The parts are not cheap, would be direct from manufacturer.

Labour wise I'm thinking 2 hours and will do a service certificate as I go so should she need insurance again she is covered.

 

[Welder]

Had a customer ask me to look at her unvented cylinder.

Cold water running through tundish. Isolate supply to cylinder and the water stops running, needs new combi valve.

She did have insurance who refused to touch it because it hadn't been serviced for 2 years.

I've advised to change t and p valve and expansion valve also so all the components are new and saves something else going in the near future. Would you say that is good advice? The parts are not cheap, would be direct from manufacturer.

Labour wise I'm thinking 2 hours and will do a service certificate as I go so should she need insurance again she is covered.

Hi Ash

So long as you replace the items with those rated exactly the same it does not matter. That said the MI police will be along soon to disagree. I only got told that by the BBA so, hell, what do they know? 😉

Why did you conclude it was the pressure relief valve? Did you disassemble it? Does the T&P not flow into the same tundish? If the T&P is fine there is no need whatsoever to change it.

What's the state of the pressure vessel? Is that pressurised properly? Remember the charge must be appropriate for the main PRV setting.🙂

You're kinda obligated ( as a professional installer) to give her a record. Ask her to keep it by the cylinder. REMEMBER. Get her agreement on doing the service at the same time NEXT YEAR and put it in your diary.
You may wish to disassemble all components you change and then silicone grease all threads and seals. It'll make it a doddle next time no matter how bad they get. 😉

 

[ShaunCorbs]

Are the expansion vessels gone or just flat ?

 

[armyash]

There is no expansion vessel, there is a expansion relief valve.

A company I worked at before used to make us change all components if it looked as though they had not been done for a while, would save getting a call back a few months down the line because a different component had failed and water was running through the tundish again. This may seem a bit over the top but it saves disputes with customers.

 

[ShaunCorbs]

so not like this?

 

[armyash]

Also can anyone recommend an unvented fault finding course. I was taught the following:

If the water running through the tundish is constant and its cold, it's the combi valve.

It's it intermittent and warm its the ex vessel that needs attention.

If it's hot it's the t and p valve.

Not the best training I admit, if I can get on a decent course that would be good. Doing the unvented course to get qualified is one thing but it was all aimed at the set up/install side from what I remember.

 

[armyash]

No it wasn't like that shauncorbs.

 

[chris watkins]

Come on Ash there must be something to accommodate expansion, either it is a bubble top or it has a vessel/s ?
If it hasn't got a vessel did you recharge the bubble, it could be that the expansion relief was discharging because the expansion was not being accommodated.
In which case it just needed a service.

 

[armyash]

so not like this?

Like this.

 

[ShaunCorbs]

internal bubble

 

[Welder]

internal bubble

On an OSO?!?

 

[chris watkins]

1. I would have felt the T&P discharge pipe to see if it was hot, if cylinder is hot then any discharge from it will make the pipework hot.
2. If it is cold then assume the relief is discharging.
3. Checked the expansion vessel & drained down & recharged the vessel / bubble.
4. Re-filled the cylinder set it to heat & check for further discharge if none then monitor, if there is then loosen the nut on the discharge side of each to confirm if it is the relief or the T&P replace as required.

 

[Welder]

1. I would have felt the T&P discharge pipe to see if it was hot, if cylinder is hot then any discharge from it will make the pipework hot.
2. If it is cold then assume the relief is discharging.
3. Checked the expansion vessel & drained down & recharged the vessel / bubble.
4. Re-filled the cylinder set it so heat & check for further discharge if none then monitor, if there is then loosen the nut on the discharge side of each to confirm if it is the relief or the T&P replace as required.

Agree. However I always removed the relief valve head and checked the seat just in case running a finger smeared with silicone grease over it so it can never stick (as rubber does when not used frequently) so ends up tearing when it does eventually get lifted off the seat.
BTW, when you do that it always leaks when put back. However by turning it a few times it reseats.
God we're anal!!!🙄

 

[armyash]

If I isolated the inlet but it's the t and p that is faulty would this not continue to run after I have isolated?

 

[chris watkins]

On an OSO?!?

Series 20 & I think 16 are bubbles Dave.

 

[Welder]

Series 20 & I think 16 are bubbles Dave.

Thanks Chris. Gosh never knew that. 🙁

 

[armyash]

I have the customers copy of the manual

Come on Ash there must be something to accommodate expansion, either it is a bubble top or it has a vessel/s ?
If it hasn't got a vessel did you recharge the bubble, it could be that the expansion relief was discharging because the expansion was not being accommodated.
In which case it just needed a service.

Has the air gap with the instructions on the side like with the megaflo. Followed that and no change.

 

[Welder]

If I isolated the inlet but it's the t and p that is faulty would this not continue to run after I have isolated?

Depends. As you remove the pressurisation from the incoming side then, if it's borderline on the pressure side, it may sit back down and seal. You could only tell that if you had pressure gauges all over the show.

Did you reset the bubble? How long did that take?

 

[chris watkins]

Thanks Chris. Gosh never knew that. 🙁

Thats because you never asked BBA. 😀🙂😉 😳

Sorry Dave just could not resist that one.🙄

 

[Welder]

Thats because you never asked BBA. 😀🙂😉 😳

Sorry Dave just could not resist that one.🙄

View attachment 36261

Swine!
Note to self: Watkins dies on Thursday...😵