Potterton Performa 28 problem and BG diagnosis/recommendation

[Tim Medcalf]

Hello

First post but long time reader so I hope someone can help.

I have a Potterton Performa 28 boiler which has been serviced by British Gas (BG) annually and has never had issues. It is probably 10 or 12 years old.

The central heating works perfectly. Radiators nice and hot all over the house.

Hot water is a different situation. The boiler will not deliver a consistent stream of hot water in the kitchen or the bathroom. Water will run hot for approx 20 seconds and then reduce in temperature to tepid before gradually returning to hot, and then cold, and so on.

This cycle will repeat on and on.

I had BG in yesterday and their view was that the system needs to be powerflushed and at least the plate heat exchanger replaced (ideally both I have been told).

Given the cost, I would be interested in people's views. (I've already googled enough to establish that BG powerflush prices are extremely high so won't use them for that even if it is necessary.)

I would like to understand why a powerflush would help the production of hot water?

I could accept that sludge might build up in the central heating part of the system and that a lack of performance in that area may merit a powerflush, but the hot water system should be separate and I wouldn't expect it to build up sludge - presumably the water comes in through the mains, is heated by the boiler and goes out through the taps?

Can anyone help me understand the issue and whether I am being well/poorly advised by BG?

Many thanks in advance.

 

[hertsboilers]

BG is right on both of them

 

[terryplumb]

The domestic hot water heat exchanger gets it heat from the central heating water running thru it. In seperate waterways within the HEX the mains cold water also runs thru and comes out your taps hot. The two never mix. If HEX is blocked it gets too hot and boiler stat intervenes and closes burner. So your tap water runs cooler ,and also cools the HEX , so burner ignites again and process starts all over again.....

 

[AGAS]

I would just change the plate just to get hw for now then sort out the shyte system because if you don't the same wil probably happen again , when getting plate changed get system water tested at same time as you may only need a chemical clean

 

[Joe 2017]

I would flush system first then replace plate heat exchanger

 

[gas112]

no need for a new plate just remove it and its a 20 min clean with brick acid , but if have seen loads of plates manky but the actual system water is relatively clean . So drain the heatin and have a check of colour of water coming out before falling for the powerflush line

 

[hertsboilers]

no need for a new plate just remove it and its a 20 min clean with brick acid , but if have seen loads of plates manky but the actual system water is relatively clean . So drain the heatin and have a check of colour of water coming out before falling for the powerflush line

Hi 112, what about scale? I have never been able to remove scale on hot water path.

 

[gas112]

i will be honest herts we only get a small amount on hw side around my way but brick acid has cleaned that like new to

 

[ReganAndCarter]

OP. Plate heat exchangers are great at catching rust particles and the water that runs through part of the hex also runs through the rads. Internal rad corrosion is where the majority of the particles come from. At the same time as fitting a new/cleaned plate hex, you should consider fitting a Magnaclean magnetic filter to catch the rust before it enters the boiler.

https://www.plumbworld.co.uk/adey-m...MIqd-qmbuy2AIVTrXtCh3Viw9TEAQYASABEgLjxvD_BwE

 

[ReganAndCarter]

Hi 112, what about scale? I have never been able to remove scale on hot water path.

Sprit Of Salts is good at cleaning both sides of the plate. Citric acid is also good for removing limescale, and is available from chemists. Vinegar will also shift the scale but needs to be left in longer.

 

[AGAS]

Hi 112, what about scale? I have never been able to remove scale on hot water path.

when the hw side is limescaled up the customer will generally notice the hw flow diminish before complaining about hw temp fluctuations .

as 112 has said I've seen this boiler with this problem when system water is quite clean especially when 10 to 12 years old

 

[Tim Medcalf]

Hello all, many thanks for the replies and also for explaining the way that the heating is achieved - that helps a lot. BG have quoted £275 to replace the plate heat exchanger and £850 to do a powerflush and fit a magnetic filter. I'll need to count my pennies!

 

[Terry lambert]

Hello all, many thanks for the replies and also for explaining the way that the heating is achieved - that helps a lot. BG have quoted £275 to replace the plate heat exchanger and £850 to do a powerflush and fit a magnetic filter. I'll need to count my pennies!

That quote is a fair bit higher than a local engineer for the same job

 

[gas112]

plate is less than 60 quid not bad BG charging 215 quid for no more than half hours work
get someone local recommended to you .
And dont fall for the BG powerflush bullsh#te

 

[AGAS]

Hello all, many thanks for the replies and also for explaining the way that the heating is achieved - that helps a lot. BG have quoted £275 to replace the plate heat exchanger and £850 to do a powerflush and fit a magnetic filter. I'll need to count my pennies!