Am I being dumb or is this a thing?

[Bazbazbaz]

I’m not a heating engineer but I’m fairly knowledgeable on the way systems work. But I have come across an issue which I’m wondering is common.

Earlier this year I had a fully licensed engineer install a new baxi combi in a property I’m doing some work on. Great job done without any problems.

Last week the owner mentioned that the shower (which is a aqualisa with a conversion box fitted to work with the new combi boiler) wasn’t getting hot.

I thought it was “user error” but having spent some time their today I cannot get it to run hot. I thought it might be the conversion box from aqualisa but the other shower which is a standard mixer unit is the same.

When I investigated further, I can get hot water out of the sink taps but as soon as I put the bath on full, the hot water drops to “quite hot”. The actual temperature that the boiler shows is 60 degrees when the sink taps are on but only 51 when the bath or shower taps are fully on.

It would seem that the boiler isn’t strong enough to heat a large enough volume of water to feed the bath or shower if the water temperature coming in from outside is too cold. And with current outdoor temperatures about freezing, this is a problem.

Or as I said, am I being dumb?

 

[ShaunCorbs]

Is the box rated for high pressure/ combi system ?

Bath taps are full bore especially if there older style and they won’t get 60 dc hot water out due to need a 40 kw plus boiler

 

[Bazbazbaz]

Yes - the box is rated for combi/high pressure.

So the boiler isn’t powerful enough?

 

[ShaunCorbs]

What’s the kw of the boiler now ?

 

[Daz_jenkins]

Whats the kw of the boiler?, and how many rads are in the property/bathrooms.

Could well be the boiler, but the engineer should of fitted something that would be appropriate.

 

[Bazbazbaz]

Whats the kw of the boiler?, and how many rads are in the property/bathrooms.

Could well be the boiler, but the engineer should of fitted something that would be appropriate.

It’s a baxi 428 which I assume is 28kw

 

[Bazbazbaz]

think there are 11 radiators

 

[Daz_jenkins]

Hmm boiler should be fine then imo mate, maybe get them to come back. They should of checked everything to makesure it was working before leaving the job.

 

[Bazbazbaz]

It heats the house fine and before this spell of cold weather the hot water was fine too it seems that the system struggles to heat up very cold incoming mains pressure water and push it through at a high temperature.

Is this a common thing?

 

[Daz_jenkins]

Not that i have come across mate , but this is defo something you want to get sorted sooner rather than later, as the weather will be getting colder. Sorry i couldnt help more