Potterton Performa 28 - No hot water from shower only

[DpchMd]

I have a Potterton Performa 28 combi boiler which has recently stopped kicking in when we turn the hot water on from the shower.

I believe the the boiler is working fine as all other hot taps in the house cause it to kick in and heat the water properly - including the bath tap, but I'm struggling to figure out what could be causing the shower issue.

If I turn the central heating on, the water heats up and the shower then supplies hot water, so the shower is definitely getting the hot water, it's just not causing the boiler to kick in independently.

Any ideas?

Thanks!

 

[stoker122]

The boiler needs a specific flow rate of water to fire up.
Try taking the shower head off and see if that fires it.
If it does, clean the head with limelight and Roberts your fathers brother

 

[DpchMd]

Thanks for the quick reply stoker. I just run up to give this a shot but sadly nothing.

The water pressure is fantastic and hasn't dipped at all since this problem started. Even with the shower head off, the boiler doesn't detect that the hot water has been turned on!

 

[stoker122]

What shower do you have?

 

[DpchMd]

What shower do you have?

Good question, it was here when I bought the house 18 months ago and doesn't have any obvious brand markings. It's probably rubbish.

Thinking of picking up a new shower valve, but I'd be gutted if a spend a couple of hundred quid and it doesn't solve the problem.

 

[stoker122]

What happens if you turn the shower fully to hot?

 

[DpchMd]

What happens if you turn the shower fully to hot?

Still ice cold

 

[stoker122]

When it is running does the thermostat regulate temp. Correctly?

 

[DpchMd]

When it is running does the thermostat regulate temp. Correctly?

Do you mean the shower temperature controls?

We did notice a few weeks back, when the shower worked, that the water coming from the shower was very hot regardless of the setting on the shower. Changing the temperature on the shower had no effect. Now of course it's cold all the time unless I turn the central heating on, or run the hot tap in the bath to trick the boiler into heating the water, but then we only get a couple of minutes of hot water from the shower.

 

[stoker122]

It definitely sounds like poor flow on the hot water. Are there any isolation valves on the inlet pipework? If so isolate the cold and run the shower on full hot to see how much water is coming through.

 

[DpchMd]

It definitely sounds like poor flow on the hot water. Are there any isolation valves on the inlet pipework? If so isolate the cold and run the shower on full hot to see how much water is coming through.

I'm afraid I'm way out of my depth here. I have no idea where to find isolation valves or inlet pipework!

I did, however, run the shower on full and then turned the cold tap on in the bath, and only a trickle of warm water came through the shower while the cold tap was on. Does this confirm your suspicions?

 

[stoker122]

Not really, as its on a combi, any lower tap being opened will cut down the flow.
Can you post a picture of the shower?

 

[tamz]

Filters or someone has closed a valve.
Phone a plumber who will have it fixed in 20 minutes if you are not confident in doing it

 

[DpchMd]

Thanks for your help so far.

 

[DpchMd]

So I had a plumber come over and he was baffled.

- He showed me that the exact same pipe feeds the hot water tap on the bath as the shower. When we run the bath tap the hot water kicks in, when we run the shower the water is ice cold.

- We stripped down the shower head and pipe and allowed the water to run freely from the mixer valve. Boiler does not detect a hot water request.

- Water pressure from the shower is fantastic, so we're definitely getting the required flow for the boiler to kick in.

- When we turn the heating on, the boiler manually heats the hot water and the shower is able to deliver scolding hot water.

- There are no isolation valves on the shower/bath inlet pipes.

He believes that the boiler is fine because every other hot water tap in the house causes the boiler to kick in and hot water is delivered. He's leaning towards replacing the mixer valve, but he's not confident this will solve the problem because the shower is able to deliver the hot water when the boiler is manually heating the water.

Very confusing.

 

[Mike Jackson]

Get someone in to check the boiler. I've had this problem on a shower with a split diaphragm in the diverter valve. Every other tap in the property worked.

 

[DpchMd]

Get someone in to check the boiler. I've had this problem on a shower with a split diaphragm in the diverter valve. Every other tap in the property worked.

Getting someone to check the boiler is not cheap, especially when all indicators point to the boiler working just fine. Could it possibly be a problem with the boiler, even though the bath tap which is connected to the exact same pipe as the shower works fine?

 

[Rickster123]

Getting someone to check the boiler is not cheap, especially when all indicators point to the boiler working just fine. Could it possibly be a problem with the boiler, even though the bath tap which is connected to the exact same pipe as the shower works fine?

It sounds like you are confident that you have found the issue. The advice mike has given would make perfect sense tho.

 

[DpchMd]

It sounds like you are confident that you have found the issue. The advice mike has given would make perfect sense tho.

Wow. I just asked a question. Nothing else. Would you prefer it if I added a smiley face next time?

I am nothing but grateful for the advice I have been given so far. I'm just looking to spend the least amount of money hence my followup question.

 

[Rickster123]

Wow. I just asked a question. Nothing else. Would you prefer it if I added a smiley face next time?

I am nothing but grateful for the advice I have been given so far. I'm just looking to spend the least amount of money hence my followup question.

Whats your problem? I simply said the advice given was valid. If you want to spend the least amount possible take a bath instead.

 

[Killy Bing]

I think youve gotten all the advice from the forum that we can give without being at your house

time to shell out for a plumber to pull things apart to find the issue im afraid.
also needs to be gas safe to touch the boiler, you can post up in the "looking for a plmber or gas engineer" section to find someone in your area.

spending the least amount of money on changing things to eliminate the problem quite often costs more than having an engineer in!

 

[DpchMd]

So my plumber decided to 'freeze' the cold inlet pipe to the shower in the absense of a valve. When we turned the shower on full heat, we got nothing. Not even a dribble. The bath tap, which is on the same pipe as the shower, was still able to produce hot water.

He's still of the opinion that it's the shower that's the problem not the boiler. But we're both still baffled as to how the shower is able to produce hot water when the central heating is turned on manually.

*scratches head*

 

[PhoenixServices]

sounds to me like the shower valve is blocked by something. It either needs cleaning out and a new thermostatic cartridge or replacing. While you have a plumber in might not be a bad idea getting them to service the boiler if you havent had it done in the last year.

 

[DpchMd]

Descaling the mixer valve seems to have done the trick!

Glad I didn't waste my money on a boiler inspection (although it was pretty obvious that wasn't the problem anyway!).

Cheers for your help all.