Worcester 24i Junior - PRV?

[Mulberry View]

Our Static Caravan has a Worcester 24i Junior combi boiler...

 

 

It's losing pressure. I re-pressurised the boiler to 1.5 bar (cold) and ran the boiler, there is water dripping quite fast out of the PRV discharge, but the system pressure doesn't exceed 2.5 bar with heating on.I'm guessing it's the PRV that's at fault? Is this it?

 

 

Any words of wisdom here? I'd be grateful... It doesn't look like rocket-science to change it?

[Mr Punter]

Gas Safe plumber would be my answer.

[Mulberry View]

2 hours ago, Mr Punter said:

Gas Safe plumber would be my answer.

 

For a PRV? When I've built a whole Nudura house without being a qualified builder?!

Edited Thursday at 18:10 by Mulberry View

[Mr Punter]

You don't need to be qualified to build a house in the UK.  ICF is fairly easy DIY.  It would be more impressive if you built in brick and block.

 

No requirement for Gas Safe if it is just for you but would be my preferred option.

[Nickfromwales]

I’m one for caution but it’s just push fit with a retaining clip. Worst thing that can happen here is you get wet tbf. 

 

Drain down, get a towel, isolate the electrics to the boiler, and get it swapped out. 
 

You'll need a lint free cloth to clean out the receptacle and some silicone grease to lube the o ring on the new item. 
 

Slight twisting motion when you offer it back in. Same retaining clip will be fine.

[Nickfromwales]

@Mulberry View

 

Have you checked the pre charge pressure in the expansion vessel? 

[Mulberry View]

11 hours ago, Nickfromwales said:

@Mulberry View

 

Have you checked the pre charge pressure in the expansion vessel? 

 

No I haven't. What's involved in doing so?

[Nickfromwales]

13 hours ago, Mulberry View said:

 

No I haven't. What's involved in doing so?

In the rear of the boiler casing is the EV (expansion vessel), usually painted red or silver, and round.

 

On this you will find a Schrader valve (same as on a car tyre) where pressure is input. Use a matchstick or similar to depress the pin in that valve to see if any air comes out (or worst case the diaphragm has ruptured and water will then be ejected).

 

If water comes out the EV is RIP.

 

If air (or nothing) comes out, then proceed as follows.

 

Blow off the pressure of the heating system off to relax the diaphragm inside the EV, you can use a drain off on the heating loop or use the PRV, and then put a digital tyre pressure gauge (or connect a pump with a gauge) on it and take the reading.
 

It should have minimum 1bar pressure but the boiler manual will tell you what it should be (I’d set this up to be the same as your cold fill pressure so about 1.5bar).

 

If it’s at any less than 1bar you need to top it up. If you find no pressure then you need to top it up and see if it’s retaining the input pressure. It’ll top up PDQ so expect to see a result within 30 seconds or so, eg the pressure gauge on the pump starting to rise.

 

If this is successful then you replace the cap on the valve and wipe your brow.

 

If it is taking much longer to get pressure on the gauge then it is possible the diaphragm has ruptured and you’re now back pressurising the entire heating circuit with air, which will eventually give you a reading on the gauge on the boiler as well as the gauge on the pump.

 

This is the final test and indicator that the EV is RIP.

 

Then you need a new EV and PRV.

 

Or, if you want to stick a band aid on this vs strip the boiler down, just buy a 3rd party EV and tee it anywhere into the heating pipework, preferably on the return side, and that’ll give you 6 months or more (until the boiler EV rusts out and eventually starts leaking).