To Combi or not to combi

[gillianp]

Hello,
We've had two plumbers over to our house to quote for a New Boiler as ours is in need of retirement.
One of them says to fit a Combi boiler which will meet our water and heating needs as well as gain ourselves a cupboard (although their quote is more expensive). The other says that a Combi boiler would not be able to get us enough hot water for our 2 batchrooms and has recommended a high "watt" Baxi.
How can I tell which of them is right?
Any advice you can give would really help even if its just how to ask the right questions!
Thanks
Gill

[dormouseheating]

hello, Worcester Bosch has a neat feature on their website. You type in the details of your home and they tell you what boiler will be suitable..
Here's the link

This should answer your question.

[dormouseheating]

if you have about £2100 to spare then there is the Viessmann 222-f

it's kind of a combi with a 100 or 130ltr water store. Floor standing, Weather compensation... looks like a fridge.

[markhurst]

If you have two bathrooms i would suggest replacing for same configuartion boiler either open vent or system combi's are good for single bathroom properties but anything bigger than that and they struggle also because there would be no stored hot water the boiler would be firing all the time your running the hot water hence bigger gas bills especially if they recommend a big kw boiler say a 40kw or 42 kw producing 17 ltrs a min. I personnaly would fit a system boiler which sealed central heating like a combi and either a high recovery open vent cylinder for hot water or a unvented cylinder which produces mains hot water giving at least 22 ltrs a min and a heat recovery time of 17 mins with 70% water drawn.

[brianclark]

Ideal do a 35Kw Logic combi which will give you anough flow to servise two bathrooms, but this also depends on your mains cold water pressure. If in dought the suggestion which markhurt gives in the preveous post is a sound solution.

[ggenergy]

Hi Gillian
Plumbers like combi boilers- nice and easy to fit no need to have any heating experiance.
System boiler with unvented cylinder if you have the water pressure/flow rate otherwise vented.
Go for a German boiler if its a long term house Vaillant/Worcester/Viessman or cheap and nasty if you are planning to move. Ideal/Baxi/Sime etc..

[familygascare]

It sounds more like you had 1 heating engineer and 1 gas fitter, one of them will have given you more choice than simply installing a combination boiler, and at least one of them should have tested the cold water tap flow rate, clearly one has more idea of your requirements than the other and he is your best bet!

[taraplumb]

General tip. when in doubt because plumbers/ heating engineers give conflicting advice, get another in for another quote.
Heating engineers tend to recommend system boilers for houses with 2 bathrooms but under the right circumstances a combi could be perfect.
Before recommending a combi the heating engineeer MUST check the mains water pressure to your property which would determine how much hot water you could get from a combi.
The engineer should also explain that if you are in the shower and someone turns on a tap or the other shower this will reduce the flow of water to first shower & can affect temperature.
If there are just 2 of you in the house and you are not having showers at the same time this should not be a problem.

A combi is NOT suitable if mains water pressure is low.
It will also be slow for running a bath.
It is perfect if you want instant hot water that never runs out.
So you have 5 or 6 people who all want a 20 minute shower, one after the other - no problem with a combi.

If water pressure is good but you do want to work 2 showers at the same time there are some combis which are up to this. I can give you a list.
In general if you want a combi I recommend Worcester bosch or Vaillant as these two are the market leaders. Less well known but also from a majot boiler manufacturer is Rehema Avanta.
AND
Despite what others say we would recommend boilers by Baxi & Potterton.

[plumber-london]

Hi gillianp! Combi boilers are usually most suitable for properties with one bathroom, although more powerful models are able to provide enough hot water for 2 showers (subject to existing water flow). Generally it is suggested to go for unvented storage system (mega flow) for more than one bathroom.

[albatross]

As per dormouse, go on worcester site to help you choose a boiler and they have local trained installers on there too.