Opinions On Boiler Repair Please

barnstar2077

Hi all,

After ten plus years my combi boiler has stopped heating the hot water properly, it is warm at most.  The central heating seems unaffected though.

I had a chap out to look at it and he says I need a new plate to plate heat exchanger and that I should also flush the radiators and dose the system with an inhibitor at the same time, to try and prevent it happening again.

As the radiator and hot water for baths etc does not mix, and the radiators seem to be working, is it more likely that the hot water has simply furred up with limescale?  If so could it not be cleaned with some kind of limescale remover, or do they pack up for other reasons?

I think I will get another person in for a second opinion, but I need educating a bit first to be honest, so any comments welcome!

jrrowleyws

Sounds like a rational diagnosis. The plate heat exchanger transfers heat from the closed water system to incoming cold water main. They aren't usually too expensive, labour will depend on how easily it can be swapped. I can do the one in my boiler in 30mins. 

Up to you if you get a power flush or not, some plumbers love them, others go for a chemical treatment then drain and refill with inhibitor later. Do you have a magnetic filter on your system?  My plate heat exchanger blocked up 3 years ago and has been fine since I replaced it. The magnetic filter did not look like it had ever been cleaned and now I do it yearly. My boiler has worked well since and as a new plate heat exchanger is less than £100 for my boiler I don't see the point in a multi-£100 power flush unless it blocks up frequently or my radiators get cold spots.

barnstar2077

jrrowleyws said:

Sounds like a rational diagnosis. The plate heat exchanger transfers heat from the closed water system to incoming cold water main. They aren't usually too expensive, labour will depend on how easily it can be swapped. I can do the one in my boiler in 30mins. 

Up to you if you get a power flush or not, some plumbers love them, others go for a chemical treatment then drain and refill with inhibitor later. Do you have a magnetic filter on your system?  My plate heat exchanger blocked up 3 years ago and has been fine since I replaced it. The magnetic filter did not look like it had ever been cleaned and now I do it yearly. My boiler has worked well since and as a new plate heat exchanger is less than £100 for my boiler I don't see the point in a multi-£100 power flush unless it blocks up frequently or my radiators get cold spots.

The guy has quoted me £800 to replace the plate heat exchanger, change two radiators to doubles, then power flush the system.  It also includes changing a pipe from copper to plastic, that drips acidic water into a drain outside, that should not have been installed in copper in the first place apparently.

So if a heat exchanger is that cheap, then a second quote is looking like it is even more called for. 

Jeepers_Creepers

barnstar2077 said:

The guy has quoted me £800 to replace the plate heat exchanger, change two radiators to doubles, then power flush the system.  It also includes changing a pipe from copper to plastic, that drips acidic water into a drain outside, that should not have been installed in copper in the first place apparently.

So if a heat exchanger is that cheap, then a second quote is looking like it is even more called for. 

The bulk of that £800 will likely be the powerflush, then the replacement of the two rads, and with the relatively minor job being the P2P replacement!

There is nothing alarmingly wrong with that quote - a powerflush is usually a few hundred in itself, and each rad will be the best part of £100 each, and then they need fitting. The P2P depends on the model, but can be got from around £35, but the 'right' part from a plumber's merchants will likely be over £100.

Like Jrrow, I've become a veteran of P2P swaps, since my system clearly has some residual sludge in it which has caused the item to block - ooh - at least a half-dozen times over the past decade. I last replaced it a week ago, along with the diverter valve and motor - the latter being about the only parts that were never replaced on my 16 year old GlowWorm combi. I don't even fit new exchangers now, but clean out the old one using brick-cleaner, which is diluted (but still strongish) hydrochloric acid - that does a sterling job of dissolving the magnetite sludge :-)

So, what should you do? If you just swap your P2P, then expect it to block again in, ooh, a half-dozen years (your first one took a decade...). So something else you could put the PF money towards  is a magnetic filter, and a dose (or two) of long-term 'filter aid' cleaner - Fernox do one which is combined with inhibitor - check Screwfix. This will slowly remove sludge from your system, and should prevent any more from forming (it's caused by your rads rusting from the inside-out...)

My P2Ps kept blocking up every year or two even with a small mag filter fitted, so it's clear that - unlike Pokémon - they don't catch 'em all. At the moment, therefore, I actually have a Magnacleanse filter plumbed in (that's the 'pro' filter used for PFs), and that's been sitting there collecting what is hopefully the last remnants of sludge for the past few months.

Still expect to pay ~£100-£150 for each fitted rad, £100 for your new filter, £30 for chemicals, and - I dunno - £150 for your new P2P.

Your call. But definitely worth getting another quote and exploring options.

The main difference is, a PF is supposed to remove all your sludge in one operation. A small mag filter will do this job slowly instead, over months. You can add more powerful cleaners, but these should be flushed out after the allocated time - from 2 weeks to around 8, depending on the product. So you'd need to factor that cost in too - it's labour-intensive. I've done all that over the past decade, so I'm now happier to use a long-time filter cleaner, and just wait....

Make and model of your boiler?

(You'll also find reconditioned P2Ps on eBay and suchlike. These should be ok to go for as a cheaper option, as it's quite straight-forward to clean them out using powerful chemicals, but your plumber will likely not be happy with this as there's no guarantee it's fully clean inside. He might, for instance, say "Fine - that'll be half the price, but if it blocks, you are on your own...")

tacpot12

The diagnosis seems off. The central heating water doesn't pass through the plate heat exchanger, so there should be no need for a powerflush. Dosing the system with an inhibitor is a good idea if it has been a while since this was last done, but it won't have prevent the plate heat exchanger from becoming blocked in the future.

A magnetic filter is a good investment; I would get one fitted if you don't already have one.  You should also get the condensate pipe replaced with a plastic (PVC) one as the condensate will eat through the copper pipe. Your engineer is correct, it should never have been installed using copper pipe.

Ectophile

tacpot12 said:

The diagnosis seems off. The central heating water doesn't pass through the plate heat exchanger, so there should be no need for a powerflush. Dosing the system with an inhibitor is a good idea if it has been a while since this was last done, but it won't have prevent the plate heat exchanger from becoming blocked in the future.

Yes it does.  The boiler switches between central heating and hot water using a valve, so it either pumps the water round the radiators, or through the secondary heat exchanger.  It's the same water, so if the heating system is full of sludge, then that sludge can be pumped into the heat exchanger, clogging it.

tacpot12

Ectophile said:

tacpot12 said:

The diagnosis seems off. The central heating water doesn't pass through the plate heat exchanger, so there should be no need for a powerflush. Dosing the system with an inhibitor is a good idea if it has been a while since this was last done, but it won't have prevent the plate heat exchanger from becoming blocked in the future.

Yes it does.  The boiler switches between central heating and hot water using a valve, so it either pumps the water round the radiators, or through the secondary heat exchanger.  It's the same water, so if the heating system is full of sludge, then that sludge can be pumped into the heat exchanger, clogging it.

Yes, of course it does! Apologies to the OP and their engineer. I wasn't thinking clearly. 

barnstar2077

Despite choosing this "company" because of reviews and a nice website, it looks like it is back to the drawing board anyway.  I emailed the guy earlier to check if the price he quoted included the VAT and got this response "Yes this is inclusive of VAT as I am not registered."

Another_Level

Its not a secret, 10year combi gas heater swap out is well known in the industry. Why attempt a repair when the existing heater has only been safety checked and not properly serviced.

Why make rod for one's own back !

Others will disagree, hopefully 

southcoastrgi

barnstar2077 said:

Despite choosing this "company" because of reviews and a nice website, it looks like it is back to the drawing board anyway.  I emailed the guy earlier to check if the price he quoted included the VAT and got this response "Yes this is inclusive of VAT as I am not registered."

I'm not sure why it's back to the drawing board, he won't be charging you vat however he still has to pay vat on the materials so he will give you an inclusive price 

barnstar2077

southcoastrgi said:

barnstar2077 said:

Despite choosing this "company" because of reviews and a nice website, it looks like it is back to the drawing board anyway.  I emailed the guy earlier to check if the price he quoted included the VAT and got this response "Yes this is inclusive of VAT as I am not registered."

I'm not sure why it's back to the drawing board, he won't be charging you vat however he still has to pay vat on the materials so he will give you an inclusive price 

Yes, you are right.  I thought at the time that it was something dodgy, but after some googling I see that it isn't necessarily so.