How Does A Condensing Boiler Heat Water ?

[CW1]

Hi,

A condensing boiler was fitted nearly 3 years ago but tenants are saying they have to wait for hot water as the immersion heater is getting hot & has to be "rested" after one of them has a shower. They've been using the immersion to heat water (the most expensive way ?).

My understanding is the immersion heater should be turned OFF & the boiler should be used, either by timer or on all the time, that will heat the water in the tank in the loft. I've asked them several times to try this, & they've had several plumber friends round, but no one seems to have taken any notice of what I've suggested.

Before I insist (or go round to do it myself !), am I right ?

Thanks

[Old_Geezer]

No expert, but as I understand it, the same way as any gas boiler does. But they recover waste heat from the steam that is normally vented.

I'd have thought that an immersion was fitted purely for emergency use. Your hot tank is in the loft ? I just have a cold tank there which supplies the pressure to refill any used hot water from the tank on the top floor.

[CW1]

Thanks Old_Geezer, that's exactly what I'm thinking. When I lived there, with the original boiler, the only time I ever used the immersion was when there was a problem with the boiler, ie. in an emergency, & that only happened once as I recall.

The cold water tank's in the loft, I don't really know how it works from there. The immersion (hot water tank ?) is in a bedroom. The water pressure in the shower's pretty poor, hence the shower pump I mentioned in a question a while back, when they thought that was causing the problem. That, apparently, is fine.

[Old_Geezer]

Maybe get British Gas to come in, check it out, and settle it once and for all ? They aren't cheap, but at least you can rely on a level of competence.

[CW1]

British Gas were round couple of weeks ago, doing the service. No issues.
I don't want to arrange an [expensive] engineer for them to possibly (probably ??!) say "use the boiler to heat your water !". I'll *tell* the tenants to try the boiler *again* 1st, failing that will have to go there myself *sigh*

[diddlydo]

Sounds obvious but have the tenants got the timer set to heat water as well as central heating? They shouldn't be using the immersion heater at all if the condensing boiler is working properly.

[bhg481]

What you're saying is absolutely right CW1. There is no need at all for an immersion heater, so long as the boiler is working. The heating timer needs to be set for the boiler to come on automatically and heat the water - it can take a while, so it should be set to come on say an hour before the water is needed. Combination boilers produce instant hot water, condensing boilers heat up a cylinder full; if your tenants are used to a combination boiler they might be expecting the instant water so you will have to educate them or even set up the timer for them.

[CW1]

I don't think they can have the timer set to hot water. They've been there nearly 3yrs, don't know if they had a combi before, but (to me anyway), if the water's not hot on demand, I'd check the programmer, not go straight to the immersion.

I've e-mailed them instructions on how to use the programmer & asked them to let me know what happens. If they suss it without me going there, they'll be absolutely kicking themselves re the wasted electricity !

Thanks everyone :)

[Ryzen]

If you have a hot water tank and an immersion heater then you have a conventional system condensing boiler..not a combi..unless you have a combi hybrid Y plan type system..which I doubt.The tenants may think they have a combi and cant understand why they dont have hot water on demand.