Baxi Solo 24 HE boiler - heat exchanger broken x3 in a year

Hi
I'm not attempting to do any DIY but wanted to get some advice and opinions.

I had 2 brand new Baxi solo HE boilers installed in June 2010. one a 24 and an 18. I had 2 old baxi's removed and replaced with 2 new ones - no alteration in anything else.

No issues at all until April 2012 when one started to leak water and stopped working - as it was still under warranty the Heat team came and changed the heat exchanger which had broken. The chap said it was an unusual fault and didn't often happen.

December 2012 - the exact same thing happened to the other boiler - it was out of warranty so I coughed up the £300 emergency cover and a lovely man turned up, changed the heat exchanger and put me a new pump on too as mine was ' a bit noisy' so I felt all was well with my world and perhaps had just had a ' faulty batch' of exchangers supplied with the boilers.

This week Feb 2013 , the exact same fault occured again with the first boiler, ring them up and this time the chap didnt have a new exchanger on his van so I have to wait a week for them to come and mend it.

He said it was 'unheard of' for 2 heat exchangers to 'go' in 1 boiler in a year , never mind 3 in 2 boilers in a year.. and suggested it was the initial installation that was at fault and said that they wouldn't continue to replace them even though I have valid silver cover for both boilers.

I asked if he would check the installation and he refused saying he just mended boilers not looked at systems ...

Question:

Could this be true ? might the installation be causing this ?

If this was the case why did it see me through almost 2 winters and continuous hot water all year before any troubles started.

I'm starting to panic here that I wont be able to get them fixed under my cover as its an ongoing problem, but don't know what else to do to put it right permenently.

My installer is a full time heating installer /plumbing chap self employed and has been around for years so I'm assuming he's experienced. He obviously put it in how he thought best, so no point asking him and I dont want to pay out to someone else to check it when I cant see how it could be at fault and surely its up to Baxi to prove its an installation issue before I pay someone else.

Anyone any suggestions or comments ?

Many thanks in advance

Taflady

I had both systems powerflushed prior to installation and both times they've had to drain down, each system has been clean without sludge .

I know I need magnets at some point added on, but the heat team man said that it was not in need right away as the systems were so clean , so I've turned my attention and funds to new windows this year.

Both are systems with open containers in the attics and those have been checked for levels which are ' fine'

Out of interest do you have a Water softner. ??

No I don't have a water softener.

Never been mentioned before - is it vital ?

The kettle and steamer doesn't furr up badly.

Thanks

two 24kw boilers add up to 48kw!!!!

from what you have said my guess is they are baking them self stupid. they are basically being put under to great a thermal strain and cracking.


what you need to do is work out what the real heat load of your home is. and try and range rate(turn down down the output) of your boilers.

just to add as people who are employed by baxi cant say this but the heat exchanger design is weak. they need the a flow and return temps to be with in given range of each other to get long life out of them.

Thanks Mehran for responding

One is a 24 and the other a 18 but they are the same model and make of boiler.

The 24 does all the hot water plus 9 radiators on 3 floors at the back of the house
The 20 does 9 radiators on 3 floors at the front of the house


Does that sound very wrong then ?.. I took several quotes before getting them installed and 4 out of 5 recommended this sort of capacity so I went with it.

So.. I need to keep the boilers turned down as low as possible for a longer life - I can do that, but additionally how can I monitor or control the flow and return temps ?

Many thanks

well, i can't see the job but it does sound off to me.

start off with this http://www.idhee.org.uk/calculator.html

if it comes bad saying you need 44kw boiler then i was be very surprised. you will need a RGi to range rate the boiler to match the load better and make sure the water flow through the boiler is enough.

you best talk to your RGI and see if he can help.

Hi ,

Its come back as 34.

So I need to get the new exchanger put in on Thursday by the Baxi heat team and then a Registered Gas Installer to come and range them both and that should help ?

Meanwhile I've turned down the functioning one to just above low and will see if the radiators maintain their warmth and will turn up a touch more accordingly

Many thanks Mehran, I do appreciate your help and advice.

It's hard when all the Baxi chap said was that it was unheard of and must be the installation.

ok, now work out if the 18 rads can even output that amount of heat you will most likely find that total output of all your rads is 15-25kw.

the idhee works out the size of the boiler need for a rapid cold to 21 degrees in one hour and even then it over estimating it.

your whole house could of been ran off one 30kw boiler.

now are both boiler ran off one pump? or do they have a pump each?

range rating a boiler is to do with the maximum amount of gas the boiler can burn(turning a 24kw boiler in a 18kw boiler for example) and not to do with the temp though turning the stat down helps with efficiency.

you have been unlucky but they crack more often then they should.

Ah ok. I'm beginning to understand this I think . A bit like a modern Ferrari engine trying to power a tiny old car and constantly revving but not being able to use its power ? Thanks.

I'm sure you're right about the radiators.. Would changing the remaining old single radiators to new double fluted ones help too ?

My house used to belong to the village plumber in years gone by and I think used client off casts and grew bit by bit and I'm trying to upgrade, thus changing the old boilers before they actually packed up.
The cylinder had 1952 on it and one of the copper pipes had 8 pinhole leaks in as many weeks after the powerflush. The pipe was eventually fully changed, taken away and tested and put down to the copper shortage of 1950, meaning it wasn't as thick as it should have been and chemicals in power flush ate it away. No problems with any other pipe 3 years on !!

They are 2 distinct independent systems each with their own pump. One at the front half of the house and one at the back . There are miles of pipe and swapping to a single system is too confusing and expensive to consider.

The joys of having a very old house....

Could the baxi man range rate it for me when he installs the new heat exchanger next week do you think ?

yes ask him to range rate, also see if they can up the pump overrun(if he can)

Thank you - I will do.

Pump overrun cannot be adjusted and on most configurations it should not be wired up for it to work

gas112 said:

Pump overrun cannot be adjusted and on most configurations it should not be wired up for it to work

Click to expand...

Sorry Gas112 you have lost me on that one ?? why would you not wire something up for the pump overrun to work ??