Unistor unvented cylinder tundish dripping

[Schrayder]

Ok thanks will do.

It’s amazing how when you ask for a cylinder service the response you get is “why”

- because customers often request a service when actually they are aware the item is faulty and needs a repair.

 

[mrbg07546]

Well I actually told them that it’s dripping and it probably needs something to be sorted. In which case I’m happy to pay additional?

 

[Madrab]

To describe how a Pressure Relief valve works.

There is valve stem with a rubber seal on the end of it, that sits on the seat of the valve body. Behind that valve seal and jumper is a spring. The spring is calibrated to resist moving until it reaches the desired pressure, in this case 3 bar. Once the pressure reaches that point the spring is overcome and the valve starts to lift, releasing the pressure, once the pressure drops then the valve spring is supposed to close the valve again.

When twist testing the top of the PRV, there are sawtooth notches in the top and when twisted the top grabs the spindle and lifts the valve seal off of the seat opening the valve, against the spring, until it reaches the top of the notch, once it passes past the notch the valve is released and the spring snaps the valve shut again, a bit like a safety top on a pill bottle, it only works one way.

There shouldn't be anything that locks and holds the seal open when it's activated, it is designed to close again once the pressure is released so I am unsure what the tech team are on about, unless they think it's a CH PRV as they invariably don't close properly once they are activated (having been in the boiler for years) and that's usually down to crap/crud/sludge on the valve seat/seal that stops it sealing again properly and then they need to be replaced. Totally different to the nice clean cold mains water that the UV PRV normally has to deal with.

 

[mrbg07546]

To describe how a Pressure Relief valve works.

There is valve stem with a rubber seal on the end of it, that sits on the seat of the valve body. Behind that valve seal and jumper is a spring. The spring is calibrated to resist moving until it reaches the desired pressure, in this case 3 bar. Once the pressure reaches that point the spring is overcome and the valve starts to lift, releasing the pressure, once the pressure drops then the valve spring is supposed to close the valve again.

When twist testing the top of the PRV, there are sawtooth notches in the top and when twisted the top grabs the spindle and lifts the valve seal off of the seat opening the valve, against the spring, until it reaches the top of the notch, once it passes past the notch the valve is released and the spring snaps the valve shut again, a bit like a safety top on a pill bottle, it only works one way.

There shouldn't be anything that locks and holds the seal open when it's activated, it is designed to close again once the pressure is released so I am unsure what the tech team are on about, unless they think it's a CH PRV as they invariably don't close properly once they are activated (having been in the boiler for years) and that's usually down to crap/crud/sludge on the valve seat/seal that stops it sealing again properly and then they need to be replaced. Totally different to the nice clean cold mains water that the UV PRV normally has to deal with.

Good to know. The plumber is coming to service and check it on Thursday . Here’s to hoping I don’t need a new EV, a vaillant one is 200 quid(and I would prefer not to get another one due to the fact it can be mounted in same spot) I will keep your updated

 

[Madrab]

You'd need to check but I don't think that the EV would have to be exclusively Vaillant. Much cheaper ones and probably the same manufacturer (poss zilmet) available.

 

[mrbg07546]

You'd need to check but I don't think that the EV would have to be exclusively Vaillant. Much cheaper ones and probably the same manufacturer (poss zilmet) available.

Yes. It wouldn’t. Specially given warranty is only 2 years . However Based on position . Mounting holes. And pipe work I prefer it to be the same

 

[Madrab]

I wouldn't worry too much about that, a competent engineer should be able to site any new EV in the same place and use the same pipework.

 

[mrbg07546]

I wouldn't worry too much about that, a competent engineer should be able to site any new EV in the same place and use the same pipework.

https://www.unventedcomponentseurop...MIs9afrueD9gIVz9_tCh07igDBEAQYEiABEgLE2_D_BwEThis ok? However I can only see they do 24L vs 25. Will this make much of a diff?

 

[Madrab]

If it's only 5 yrs old I doubt the EV will need replaced, just re-charge but never say never, what size is the cylinder? post a pic of the UV and EV data plates if you can

 

[mrbg07546]

If it's only 5 yrs old I doubt the EV will need replaced, just re-charge but never say never, what size is the cylinder? post a pic of the UV and EV data plates if you can

vaillant 250/3 unistor. Says 245 litre. I got the part number of vaillant for their EV. It’s 200 quid

 

[Madrab]

As a guide then yes a 24>25L vessel would be needed for a 250L. A rule of thumb is around 10% of the store's volume.

If you want to keep it true to the system then a compatible 25L vessel could be used

https://www.unventedcomponentseurope.com/vaillant-25-litre-potable-water-expansion-vessel.html/

 

[mrbg07546]

As you can see it’s mounted against above a vent . It is blocked out at other end. So I was looking for mount in same region

 

[Madrab]

Invariably the larger vessels have the same integrated mounting bracket like that. They don't tend to use the separate screw tight bracket/band types. Always good to check though.

I wouldn't worry about it until the old one is condemned though you are looking to get Vaillant out to do the service, they £99 isn't too bad BTW. If so though and it needed replaced, they would replace it with a Vaillant item at the typically increased cost.

 

[mrbg07546]

Invariably the larger vessels have the same integrated mounting bracket like that. They don't tend to use the separate screw tight bracket/band types. Always good to check though.

I wouldn't worry about it until the old one is condemned though you are looking to get Vaillant out to do the service, they £99 isn't too bad BTW. If so though and it needed replaced, they would replace it with a Vaillant item at the typically increased cost.

Vaillant back tracked and said they don’t service cylinders. They will look at them at most. It’s a real flaw in the model. So a local plumber with g3 is coming to service both for 100. If the EV needs to be replaced it would obviously cost more. I did get a prv valve from tool station incase. And I’ll return it if he doesn’t use/need it.

there is no service plan or option of service vaillant offer on the cylinder. They told me to ring vaillant advance engineers. i rang the nearest 5 “vaillant advance” plumbers for a service. The minute I said tundish is leaking they refused job and even said “no one will do it” the other told me I need a EV and and new prv. And quoted me based on that. Without even looking.

I did previously contact HomeServe and BG for a policy. They offer boiler and central heating. Which does cover the unvented cylinder. But I was not eligible to buy the product as terms state “if boiler is under manufacturer gaurantee you can’t take the policy.” Even if I wanted to exclude the boiler element and was paying for a element I did not use.

next time I will purchase megaflow. I would lose out the functionality to set the cylinder tempreture on the app AND the hot water boost function but I can probably live with that.

To compile to the misery the shell has gone a bit loose. Vaillant came down and said it’s coesmtic and can’t cover it (there’s a additional 25 year cylinder gaurantee , which only covers the inner shell).

I have started a complaint to vaillant out of principle .

 

[Madrab]

I did get a prv valve from tool station incase

Just remember, it isn't just any old PRV that can be used, it needs to fit to the control group and be rated to 6bar.