Combi KW question

[Jurassicspark]

Hi peeps,
Got a valliant boiler installed, it can output 34kW. No tests/inspection were done when installing this boiler, was just chucked and drilled in.
My old condensing boiler outputted 15kW.

Now, I have a 3 bedroom house with only one bathroom with a radiator installed in every room. No rubbish tanks etc. I have one shower that's it.

I heard that this can make my bills spike up as the boiler will first start up very high then go back normal then go high etc, cycling basically. Overpowered boiler?
When i turn on the hot water tap at first the boiler makes a sound identical to a jet engine then eventually it will lower its sound however if i turn the tap on very slightly the boiler have a low sound at first..

Can someone please advise on this?
Thank you.

 

[Mottie]

The 34kw is for constant hot water. I doubt if it will use that for your central heating. My 18Kw heat only boiler sounded a bit jet-like on startup when it was installed but I’ve since adjusted it to a max of 14kw which makes it a fair bit quieter.

 

[Jurassicspark]

Thanks for that quick reply.

Was just watching tomkat gas training and the bloke said that most ppl out there are chucking oversized boilers in properties nowadays.
My gas bill is quite high... alarm bells ringing. It costs me £3 just for 5 people having a shower...

 

[Johntheo5]

I think the uk gas price is capped at 7p/kwh if so then the 5 people are showering for 13 minutes each at 16.8LPM at a showering temp of 40C, from mains at 11C.

 

[fixitflav]

Hi peeps,
Got a valliant boiler installed, it can output 34kW. No tests/inspection were done when installing this boiler, was just chucked and drilled in.
My old condensing boiler outputted 15kW.

Out of curiosity, whose idea was it to change to a combi? There has been some discussion about this, eg on this thread

Is switching to a combi boiler in a large-ish house really such a bad idea?

Hey all, I'm trying to get my head round this. We've got an ageing system with an 18 year old 24kW system boiler and a similarly aged megaflow water tank. The boiler has been on its last legs for a while and I want to replace it. The problem is that I don't want it in the same place as it is now...

www.diynot.com

 

[Jurassicspark]

Out of curiosity, whose idea was it to change to a combi? There has been some discussion about this, eg on this thread

Is switching to a combi boiler in a large-ish house really such a bad idea?

Hey all, I'm trying to get my head round this. We've got an ageing system with an 18 year old 24kW system boiler and a similarly aged megaflow water tank. The boiler has been on its last legs for a while and I want to replace it. The problem is that I don't want it in the same place as it is now...

www.diynot.com

Well .. old condesing boiler stopped working so i got a xombi

 

[fixitflav]

Well .. old condesing boiler stopped working so i got a xombi

OK, just wondered whether it was your idea or the installer's suggestion.

 

[Johntheo5]

Well .. old condesing boiler stopped working so i got a xombi

What exactly is your problem?, you can reduce the boiler output on CH to match the heat demand, if your max heat demand is say 15kw then you can set parameter d.00 to 15kw, it won't affect your hot water output. If you think the HW usage is costing too much then put restrictors in the shower heads.

 

[Jurassicspark]

What exactly is your problem?, you can reduce the boiler output on CH to match the heat demand, if your max heat demand is say 15kw then you can set parameter d.00 to 15kw, it won't affect your hot water output. If you think the HW usage is costing too much then put restrictors in the shower heads.

Thank u.
How do i restrict the central heatingvto say e.g 15kw

 

[Johntheo5]

Try this.

Vaillant ecoTec Plus 418 D0 Setting

Can't see why you can't at least access the d codes as there are numerous posts re the householders changing the parameters including d.0, it must be relatively simple to do this and allowed by vaillant. If the boiler wasn't serviced since the extended warranty work (PCB etc) then they should...

www.plumbersforums.net

 

[Jurassicspark]

Ty