Which boiler for 2 bathrooms?

10 Nov 2008
Reaction score
United Kingdom

Apologies to all you who may have answered this question many times before but I couldn't find the exact answer when I searched the forum.

I'm currently planning a house renovation and need to come up with some specifications for the tender package which my architect is putting together.

The house we're renovating is a semi detached and we plan on converting the loft so that we'll have 2 full bathrooms. I'd just like advice as to which boiler system I should have installed. My architect is recommending a Vaillant (not sure of the model) which could apparently power the two bathrooms and heating but is a bit bulky. Also we've been recommended a mega-flow system. The boiler would be housed on the ground floor so it would need power to get up to the second and we don't plan on having a tank for the system so would like to know what the professionals would recommend in this situation.

Any help greatly appreciated (and once again apologies to those of you who have answered this question too many times to care).

Sponsored Links
You need to ascertain the pressure and flow rate of the water supply available to you before you can make a decision.

Flow being the more important of the two.

While the 2nd floor bathroom will be the guest bathroom I wouldn't want a sudden drop in pressure if both showers are being used at the same time or if the washing machine was on etc. Even pressure and heat distribution throughout.

We'd like to avoid having a tank so it would be a pumped system throughout rather than a gravity system.

I will have a chat with the architect
if your cold mains pressure is great into the property then worcester bosch do a greenstar 440/550 or 37/42 cdi which will power hot water into two showers at the same time. i'm sure vaillant are the same only i generally only fit worcester.

if your cold water in is poor then you will have to look at stored hot water, unvented cylinder etc!
Sponsored Links
Two bits of advice here.

1. Let the architect do his bit, and make sure he doesn't stick his big nose into anything to do with plumbing or heating. Architects are not plumbers, let alone heating engineers, and they don't know Jack about it.
Find yourself a good heating engineer, and let him sort the heating out.

2. Stay far away from Vaillant. Although the boiler in itself is not bad, the company is without a doubt the most terrible of all brands when it comes to aftersales/customer service. If you ever get a problem with your boiler ( chances are that sooner or later you will ), you'll have agro to no end if the system is based on a Vaillant, and probably very high cost.
if your cold water in is poor then you will have to look at stored hot water, unvented cylinder etc!

Unvented cylinder? These operate on mains pressure. The same applies to these as in any mains pressure appliance.

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local