Advice/opinion on hot water system please?

[trick97]

Hi,

I previously had a megaflo 210i indirect unvented hot water cylinder supplying my home. It was about 8 years old, worked perfectly with high pressure water supply, only had to heat it for 30 mins each morning and was fine for the day with multiple showers, bath etc. I have 3 separate showers in the house and you could run all concurrently without any noticeable drop in pressure and constant temperature. If someone ran a tap the temp of the water in the shower would not change.

A few weeks back the Megaflo had a leak from a seal on the side (not the immersion but something else). I have British Gas homecare cover so they came out and decided to replace the cylinder. They didnt replace like with like brand but instead installed an Ideal Instinct 200. I was told the only difference was that it had an external expansion tank as opposed to the integrated design of the megaflo, and there should no change in operation /performance as before.

This isnt the case.
A few things that have been happening:

Run a shower (which is about a metre or so away from the hot water cylinder) on the same temp setting as i used to run it before the cylinder change....after 30 seconds to a minute a funny noise comes from the hot water cylinder and the water pressure drops slightly and the temperature goes luke warm. I can turn the temperature up in the shower to compensate, but then if i forget to turn it back down before getting out and then next day turn it on, its too hot. Previously it stayed on the same temp and I never had to change it. I dont even remember ever changing the setting in years.

Secondly if someone runs a hot water tap the temperature changes in the shower, fluctuates hot and cold. Didnt do this before.
I also tried this with a tap as opposed to a shower, so ran a tap on a warm setting, tried another tap or the bath and yes the water temperature fluctuates. Never would have tried this with previous system as never needed to check it. Presume it didnt do it.

Tried a different shower that the kids use, its further away from the hot water cylinder but does the same thing.

British Gas (or rather Dyno) claim there is nothing wrong with the system and said if anything it was a problem with the showers. I said but it never did it before so why now? also at that point i hadnt tried the taps, but as it does it there too then its not the showers.
They have pretty much left me with a poorer functioning system which i am not happy about. They say it cant be the hot water cylinder as its the same pressure as before, still get plenty of hot water etc. And basically "tough".

Another thing ive noticed which may just be me focusing on it so much is that when the washing machine is on and there is a demand for water it makes a loud bang noise as if its banging on and off when using that water. I never noticed this before and the washing machine is always on! May not be linked.

Is there such a performance difference between those two cylinders i have mentioned that could explain why this is?
I also thought the advantage of having a system boiler and cylinder system was to meet the demands of a busy home (its a 5 bed with high occupancy)? if i had a combi system then yes i could understand.
But never experienced any of this before, and i bought the house new 8 years ago.

So not sure where i stand now. I have submitted a complaint but wanted some independent opinions if possible please?

[aeromech3]

Though they appear in spec to be similar and should perform same, the Megaflo is a more expensive unit and 8 years is poor but within warranty.
Sounds as if there is trapped air pocket in the cylinder, but that is my educated guess.
When you say only had to heat it for 30 mins, do you mean with the boiler or immersion?
Your boiler model and year?

[trick97]

30 mins with the boiler, never use immersion.

Boiler is a potterton promax and of similar age as the megaflo (was).

[aeromech3]

Only guess either air or during fit introduced a blockage (crushed kinked pipe) ; call them back.

[trick97]

When you say a crushed pipe, do you mean something I can not obviously see from the sides of the cylinder?

[aeromech3]

Yes if there are such!

[wine~o]

trick97, either the pipe issue above or a valve partially shut. Pic/s of the cylinder may help.

[London mike 61]

As an aside , we ditched British Gas homecare cover this year because of the rapidly dwindling service and massively over priced boiler cover especially for a boiler that’s only 7 years old.
We went with BOXT boiler services because our youngest son has them and he highly recommended the company to us.

Worth finding out how much you could save and getting a better service.

Mike