Hot Water issue - Potterton Puma 80e

eddieed · 9 May 2014

Can someone help, we have the above boiler.

The hotwater pressure has dropped and the temp of the water is scolding.

Any ideas, we have a maintenance and repair contract and they have changed the theromstats for the Hot Water and Central Heating but it hasn't worked. I think I could have told them that! He is now blaming a lose cable, not sure about this either if I am honest.

At the end of my tether with the company as we reported it Sunday, but they still haven't fixed it. I want to give them a chance as I don't really want to pay twice and have to call out a local engineer, but at the same time Chocolate Teapot is a phrase that comes to mind.

Agile · 9 May 2014

There are several possible problems!

Blocked filter, jammed hot start device etc.

But regardless, the temperature control in the boiler should still manage the temperature properly as long as the gas settinge are correct.

These boiler cover deals are so cheap don't expect to get good engineers from them. No experienced engineer will want to work for them!

An independent needs to be a bit better! Or will end up with no customers.

Tony

eddieed · 9 May 2014

Thanks.

He has spent more time on the phone than looking at the boiler, hasn't a clue. Problem is I think the pressure is so low that even at its lowest heat setting the water is coming out scolding. Cold water presure is fine and central heating is fine as well.

When he originally arrived he said it was something the boiler didn't even have, without even looking at it. Thankfully my wife made him look at it and he discovered as it didn't have one of those parts it couldn't be that!

It is the only thing we have a contract for in our house. I have a morbid fear of being ripped off by heating engineers for some reason or finding a cowboy and them doing something which kills my whole family! I realise there are good ones out there but I just have this fear of always finding the bad, I don't know why so sorry to all the good ones!

I certainly wont be going with nPower Homecare at renewal, second time they have let me down, at least BG would fix within a couple of days, but may just go for saving the monthly payments into an account to cover any fixes needed!

eddieed · 9 May 2014

So after nearly 2 hours, of which he spent an hour and 45 mins on the phone he has decided that the Heat exchanger has gone.

He is now saying that makes it beyond economical repair and that they part is obsolete anyway.

Ignoring the beyond economical repair bit, can anyone confirm that this part is no longer available.

Gasguru · 9 May 2014

If the cold water pressure and flow are fine then there's only a few things in the boiler that could cause the flow problem.

Did he remove the cold inlet isolating valve and check/remove the flow isolator pressed in the end? They can easily block up.

Occasionally the water saving valve can stick preventing full flow but I've never come across that fault.

Temperature control on the Puma is never that great especially now they are ancient.

The heat exchanger could have scaled up. This has been an obsolete part for several years. Pumas are now getting on for 20 years old.

eddieed · 9 May 2014

Thanks Gas guru...to be honest I do not know. He changed the temperature sensor and then from what I can tell spent most of the time on the phone, then announced that it was the heat exchanger.

I am going to ask them to send out another engineer to have a look at the things you have mentioned, I don't have much confidence in the first.

We have had a heat exchanger before, about 6 to7 years ago I would say, I find it strange it has scaled up as we have a water softner!

So if it is then confirmed as the heat exchanger then it looks like a new boiler, annoying as we are thinking of moving house. Know any good fitters in the Reading area? The best nPower will do is knock me £450 off installation from one of their sellected installers (who probably add £450 onto the quote first)!

Joe4542 · 9 May 2014

The heat exchanger bore on these has such a large CSA that the DHW side is very unlikely to block or scale to the degree that it would restrict the flow.

The problem is almost certainly the DHW thermostat/flow limiter not opening up when the temp rises.

If you turn off the boiler and run the hot tap until cold, then turn the boiler back on, you should see a clear increase in water flow from the tap after 15-30s, if not, then that would defo suggest likely problem as there aren't other restrictions/filters in the water path (and presuming no one has turned down your cold inlet valve).

These do run very hot anyway, when able to reach their desired temp (ie little flow).

The Heat Exchager on these IS obsolete, apart from finding someone still holding stock, they are no longer in production, interpart sold thru around a year ago. Although I would have to say it sounds like the eng was just too incompetent to find the fault so just found something that would prevent the job from remaining to be his problem!

Agile · 9 May 2014

Oh dear!

Although slightly different this is really a very simple boiler to work on.

It is most UNLIKELY to be any problem with the heat exchanger. Even if it was then it can be cleaned. They only need to be replaced if leaking ( as I did for one last year).

No on has mentioned checking the filter on the water inlet!

This is really a very simple boiler! The water aver device, although the obvious suspect perhaps, is never ever failed in practice. Even if it did the inside can be removed to solve the problem.

All you need is a competent engineer! You don't get many working for those cover firms!

Tony

Joe4542 · 9 May 2014

Tony, whilst I agree in principle, I've only ever found 2pumas where they actually bothered to put the filter in ISO valve, even then, being the cold mains it isn't subject to lime scale as much as hot side.

Then as for flow stat, yes they don't fail often but I've had to swap 3 in last 3yrs, I'm sure you've changed many puma waxstats in your time, whilst they undoubtedly have a harder life, it's basically the same thing - just different set points.

On last point, agreed, OP needs someone who can use logic and reasoning to diagnose a fault.

Gasguru · 9 May 2014

Maybe no filter in the isolating valve but it does have the flow limiter pressed into it....and that's the first item to check.

eddieed · 10 May 2014

Thanks all for the help and advice.

I have asked the company to send another engineer, someone who knows what they are doing they are doing this on Tuesday. The main thing that annoyed me about the other bloke was he just kept saying its old, that's not an excuse to throw it away for me!

I have turned the boiler off run the tap until cold then turned the boiler back on. There was a minimal increase in the flow but not much. The CH side is all working fine by the way.

Can someone please give me a list of things I should ask him to check on Tuesday, I have got a bit confused from the above postings.

Finally if it really is the heat exchanger then I have found a couple on eBay. What would be the rough cost of getting a local engineer to fit one of these. Normally I wouldn't bother but we are probably going to move house in the next year and I am not sure I really want to fork out £1500 on a new boiler that I will never use and won't add any value to the house, although it may make it easier to sell!

pallen5000 · 10 May 2014

Agile said:
T

These boiler cover deals are so cheap don't expect to get good engineers from them. No experienced engineer will want to work for them!

Biggest load of b*llocks I've ever read on this site. So all independant plumbers are amazing and none are cowboys?? Wake up!!

Agile · 10 May 2014

The one that I had to replace I charged £330 to supply and fit it but it was some way away and would have been less if closer.

But in the rare event that it was at fault then it can still be cleaned. But only by someone minded to do it and who knows how to do it.

But to put the matter in perspective, what is your flow rate in litres per minute?

Also if you see the FAQ, what is the minimum gas rate with the boiler supplying hot water to a basin after a few minutes?

Tony

Tibbot · 10 May 2014

pallen5000 said:
Agile said:

T

These boiler cover deals are so cheap don't expect to get good engineers from them. No experienced engineer will want to work for them!

Click to expand...

Biggest load of b*llocks I've ever read on this site. So all independant plumbers are amazing and none are cowboys?? Wake up!!

The blokes who carry out work for the insurers usually are independents. It seems you've misunderstood the comments made.

eddieed · 10 May 2014

Thanks Tony

The flow rate is 4 litres a minute once the water is hot. I would say its about half what is was?

We have 2 children, filling the bath is a pain and we can't run 2 taps at a time anymore.

Where are you in London don't fancy a trip to reading do you!

diynot

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Hot Water issue - Potterton Puma 80e

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