Now at my wits end with my Powermax!

[OllyA]

Hi-firstly, thanks for looking. Right, i'll attempt to describe the list of symptoms as accurately as I can:

I have a 7 year old Powermax Range 160 combi boiler. I moved into my house in 2007, and a neighbour warned of the problems she had with hers. She's been advised that it is not a boiler designed for hard water areas (which I live in), and due to this, has to have her system flushed annually. In 2007, we started losing hot water pressure, then temperature, unill we had virtually nothing. The central heating and cold water remained fine. I had BG out, who diagnosed a blocked plate heat exchanger, and put a new one in. I kept the old one in the hope of unblocking it using chemicals, so I could swap the 2 whenever one became blocked. The BG Engineer confirmed they had replaced the heat exchanger 2 years prior to this. One year passed, and we've lost just hot water now. The pressure is ok as is the central heating, but over the last 2 months it's got progressivley worse, up to now, where we have none at all.

I can't imagine the heat exchanger becoming blocked in 12 months, can anyone advise a possible cause/remedy? Apparently the only way to cure this problem permanently, is to either replace te boiler, or fit a water softener-both of which are to costly at the moment, as I have a young family.

Thanks again for looking, Olly.

 

[Range185]

In my experience of Powermax boilers, I would say the most likely culprit is the Blender Valve Part No. P757.

These scale up like hell and normally have to be replaced every 2 years or so, I'd make that your first port of call.

 

[OllyA]

Ok-thanks for your help, is that a specialist job?

 

[Onetap]

She's been advised that it is not a boiler designed for hard water areas (which I live in), and due to this, has to have her system flushed annually. In 2007, we started losing hot water pressure, then temperature, unill we had virtually nothing. The central heating and cold water remained fine. I had BG out, who diagnosed a blocked plate heat exchanger, and put a new one in.


I can't imagine the heat exchanger becoming blocked in 12 months, can anyone advise a possible cause/remedy? Apparently the only way to cure this problem permanently, is to either replace the boiler, or fit a water softener-both of which are to costly at the moment, as I have a young family.

IMHO it is quite plausible that the domestic hot water heat exchanger could become blocked in 12 months; the mains water supply in Kent usually has high levels of dissolved chalk (family near Maidstone). This will block the heat exchanger in any combi boiler, not just the Powermax.

Note that the above refers to the secondary (domestic hot water) side of the brazed plate heat exchanger (BPHX); there is no good reason why the primary (boiler/heating) side should get blocked.

The heat exchanger can be descaled, but they can become totally blocked with scale, preventing descaling solution being pumped through the waterways. There is also a risk that descaling will uncover leaks in the BPHX. Given the risk and the unavoidable downtime involved, most companies would just fit a new replacement.

The blender valve can also fail, as Range185 has said, but I'd suspect the BPHX in your case; we won't know until you've fixed it. You can also get a similar symptoms if the PHX pump (which pushes boiler water through the primary side of the BPHX) fails or if the pump's high- temperature cut-out trips.

The installation instructions recommend the fitting of a 'scale control device'. Range supplied an electronic device as an optional extra, which I found surprising since I've found them to be pretty useless. The cheapest option (if it is a scale problem) would be a Combimate. These put food-grade phosphates (I think) into the cold water supply, which makes the scale less likely to form deposits. The best solution would be an ion-exchange water softener.

Did you try descaling the original heat exchanger?

 

[OllyA]

Thanks Onetap-no, I haven't got round to it yet. I think the best bet is to get someone out to have a look-by the way, how much is on of those ion-exchange water softeners?

 

[Onetap]

Thanks Onetap-no, I haven't got round to it yet. I think the best bet is to get someone out to have a look-by the way, how much is on of those ion-exchange water softeners?

At a guess, £400 or £450 to buy one, depending on the type. Probably £600+ fitted. By ion-exchange I mean the salt regenerated type, to distinguish them from the electric and magnetic devices that are sold as 'softeners', but aren't.

 

[OllyA]

Ok-thanks for that, very helpful!

 

[baxpoti]

I have a 7 year old Powermax Range 160 combi boiler.

Have you?

I've never heard of it!

 

[gas4you]

All the old powermax's that I fitted, and that is quite a few when I was on site work, had some sort of scale device fitted as standard, the electric coil around the pipe type.

Has yours not got this?

baxpoti will confirm or not.

 

[Range185]

I have a 7 year old Powermax Range 160 combi boiler.

Have you?

I've never heard of it!

I reckon the poster means a Powermax 140, or possibly 185 thermal store.

 

[Range185]

Ok-thanks for your help, is that a specialist job?

OllyA,
I still reckon its most likely to be the Blender Valve, as they are notorious for scaling up and subsequently fail and dont distribute the hot water properly, and you end up with luke warm water.

Check the copper pipe vertical tee section above the blender valve, with the tap running on hot, and if the pipe is hot to touch then hot water is present, but is not being mixed correctly by the blender valve.

They are easy enough to replace, I think a new one is approx £75 to buy.

 

[OllyA]

Cheers guys-yes, it was a 140, and plumber confirmed it to be blender valve today-thanks for all your help.

 

[OllyA]

Right-fitted new blender valve over the weekend, and when the heating is on, I have the green "Burner" light on the boiler, and all is good-hot water and pressure are almost back to normal. However, when the heating is off, the hot water is almost non existent, and the pressure is poor. I can't get the "burner" light on when using the shower etc....oh the joy!! Any ideas? Thanks.

 

[OllyA]

Anyone at all?? Could really do with a hot bath tonight it's been months!!

 

[Range185]

Oh aren't these boilers bloody annoying !!!! I've got a prob with mine now, although very different to this.

Obviously it wasn't just the blender valve then. I wonder whether it is not full of water in the thermal store and is cutting out ? Has it been drained recently at all ?

These stores have a safety cut out that comes in if the store isn't full of water, but they can be reset with a red button internally.