DIY Doctor UK DIY Forums

Hi folks, newbie here. Not strictly a DIY question, but still hoping someone can offer advice. I need to replace my current gas boiler, to anyone ufortunate enough to have come across one, it's a Powermax 155, so we don't have a hot water tank at the minute. Property is 5 bedroom, two bathroom, 13 radiators in all. I've have the usual suspects around to give me a quote, British Gas an Npower (expensive, I know), and both suggested a combi boiler (BG = Worcester Greenstar HE 440 , Npower = Vaillant ecoPlus 937). Thought I'd ask a local Vaillant approved installer for a quote and he's completely thrown me. In his opinion, I'd probably be disappointed with the performance from a combi in this size of house. His recommendation is to go for a system boiler and a pressurised cylinder, probably 260 litre capacity. He reckoned this would be more expensive to install, but would deliver must better performance. Anyone any thoughts, or point me in the right direction? TIA

Hi as a leckie don't usually say much in this forum but as I get to connect up many boilers for local plumbers I can say that most people are dissapointed with hot water delivery rate at taps, showers etc. as flow slowed down thro' boiler to give time to heat water in heat exchanger,
regards SPARX

If you have more than one bathroom then a combi isn't the answer. Go for an unvented hot water system as suggested. This would give you mains pressure at the hot taps and plenty of hot water to fill two baths simultaneously. More expensive to install but very efficiant. 1 degree heat loss during 24 hours on your cylinder.

My 210 litre indirect cylinder, with static head from header tank in the loft, is heated by a 40,000 BThU/hr gas boiler, in a 3 bed-room house.
Having a shower is sometimes chilled when another demand on the hot tank arises, eg kitchen sink, or washing M/C. A pressurised system with larger tank and boiler would definately be advised for your size of home, and likely use of 2 mixer showers ; ---- you may even avoid using a pump-assist on your showers. Take advice on your choice of boiler ; -- my balanced-flue unit has no fan to give trouble, and in all 10 years, has been totally reliable. Some brands are known in the trade as more likely to give bother than others.

thanks for the responses folks.

Back again folks! got another quote from a local Worcester installer that's muddied the waters yet again. He's convinced that the Worcester Highflow 440 combi is more than adequate for the property. He's given me quotes for both this boiler and a system with tank, so he's not pushing me down one path. Anyone got any experience of this combi boiler?

hi as an engineer of45 years i concur with dr-plumb you need without dought a pressurised h/water cylinder and standard boiler all the best john

thanks for the input Johnb