Advice on boiler.....service/replace?

Hi all,

so we have a baxi 105e combi (i think) in the attic and recently our thermostatic shower has been intermittent with the flow of hot water. It often reduces in flow and/or reduces in temp, going quite tepid and back to hot again.
My step-son who is 'almost' time-served in his plumbing apprenticeship says that due to the current colder weather the boiler is struggling to keep the water at a constant temp to feed through the shower at the rate we want/expect as the cold feed from the street is much colder. Which makes sense i guess.
How can we improve on this; service the boiler? replace it? Is it any good anyway?
We're in a 3 bed semi with a downstairs toilet, family bathroom with power shower and en-suite with thermo shower.
The time is takes for the kitchen hot tap to produce hot water can be up to 2 mins sometimes, even in milder weather, which is crazy imho.
The boiler was serviced last year and the plumber said it was in decent condition (its about 7 years old we think).

I have entertained the idea that it may be the actual thermo shower being a little 'off' as i remember reading in the instruction that you can adjust the thermostat and flow of it (by almost taking it apart), but my step-son assure me this isn't the cause of the issues as he tested the bath tap and sink tap and the same temp fluctuation occurs.

Any advice on the best course of action?

Thanks

As the temp fluctuates on the shower and the taps it is very likely to be a blocked plate heat exchanger. Your step son is incorrect to diagnose the fault is because of lower cold feed temps. The plates can be cleaned, but it is often considered better to replace it. Not a bad boiler at all, but has limitations on flow rates, and it is considerably older than 7 years. About an hours work to fit a new part. Part would be about £70.

Thanks, appreciate the advice.
If we decided to replace the boiler what would you recommend? And do you know approx costs for such?

Thanks again.

You should not fit a lower power than your existing 30 kW model.

But it probably does have a few more years life in it.

A replacement would be about £1700 to £2100 fitted for a good quality make.

Tony

Thanks for the advice again.

Got my regular boiler engineer coming round on friday to check it over. He did advise looking to replace it as its pretty old.
I was reading on another forum that an upgrade model of the baxi, which would obviously be a much better boiler would fit in the same place with the same pipe entry/exit holes etc, so minimum disruption and re-piping.
If this is viable then it could save quite a bit in labour charges.
My step-son may even be able to fit it and have Neil (boiler engineer) test and certify it.
We'll see what he says on friday.

Baxi duotec will fit directly onto the existing jig with no pipework alteration at all and comes with a 7 year g`tee .
Minor alteration to existing flue hole position and new condense pipe req.

But as has been said the plate can be cleaned or replaced .

Also you say the shower reducing in flow well that indicates a shower cartridge fault not a boiler fault.


If its 7 years old then it will prob be a 105HE and as well as cleaning the plate the venturi in wAterside of it will probably need changing (costs under a tenner)

It's worth checking your shower head is not scaled up too. This can cause low flow through the boiler which causes it to cycle on and off and hence hot and cold output rather than providing a constant flow of hot water that the shower prefers.

Does it still do it if there is another hot tap running in the bathroom?

Guys, sorry if i misled; the shower isn't reducing in flow as much as its reducing in temp, its going, hot-cold-hot-cold etc etc.
And i'm assuming that because its a combi then colder water will flow much faster than hotter water(?), hence my comment about the flow changing; when really its the temp changes that are the concern.

The boiler we 'think' is at least 7 years old. (not even sure where the wife came up with that number from) but i'm pretty sure its a 105e (not HE).
If it were a 105HE then it looks like its a decent model as its a condensing combi with 87% efficiency rating, whereas the 105e sucks as its non-condensing with a 78% efficiency rating.
http://www.homeheatingguide.co.uk/efficiency-tables.php?make=Baxi

Just get the plate cleaned , or change it for around £50, both jobs not even near an hours work.
As for efficiency that is the maximum efficiency the condensing boiler will work at with everything purposely designed for them and set up correctly in a normal house set up they only hit that target for a short while whilst running .
So if your thinking you will save a fortune by changing then this is not going to happen