During the last winter my private water supply froze and destroyed the pump which pumps up water from a source below our house but I could still at least operate my central heating system as the heating circuit is separate from the water system and is protected by anti freeze My neighbour who also has a private supply but gravity fed could not operate his heating system as the boiler required 2 bar pressure. His boiler is a combi type My question is can you get a combi boiler which does not require pressure to operate? Blair Malcolm
Your last point was a good one. In the case of my neighbour the plumber installing his new system recommended a combi boiler on the grounds of efficiency without explaining the limitations. Now he understands the limitations! Blair
I used to feel the same way - but I had a Worcester Bosch combi installed two years ago and could not be more pleased with it. We were able to remove the airing cupboard from the bathroom and install a walk-in shower instead. The storage tank and CH header tank in the loft were removed so there is no plumbing up there at all now. Our gas bills have reduced dramatically as we are only heating water as and when we need it - rather than heating a full cylinder of water every day - most of which is not used. The installation of our boiler coincided with a big increase in gas charges - but our Direct Debit actually reduced at the end of the first year (and we got a refund because we had overpaid!).
Provided you get a 'good' combi with sufficient power to provide a decent flow of hot water, then the advantages seriously outweigh the minor downsides IMO. In fact the only downside, for us, is that the bath takes a bit longer to fill than it did under the old system - but in view of the fact that we rarely now take a bath, preferring to shower, that is hardly a major disadvantage. The extra time it takes to fill the bath is not significant either.
so critcher said...................... YES because the header tank only supplies topup water, the water in the system is at no pressure above head system pressure, which can be as low as
2 or 3 feet head. the system will work at nil pressure,except for the pressure created by the pump.
You also changed to a more efficient boiler. You would also have made savings by just changing the boiler and improving any controls to the system. You may also have got lucky with the installation. Many combi boilers are some distance from the hot taps and every use of the hot tap leaves a long length of pipework that will cool down.
For a couple or a single person then a combi is usually a good solution. I like the HW on demand as I never have set times for coming in from work. I am however not able to come in from work throw all my clothes into the washer and then go for a shower as the pull of two appliances causes the shower to struggle.
The central heating side of the system is sealed. So once it is up to pressure then it will not matter if there is any pressure to the cold water supply.
I suspect that your neighbour probably had a frozen condensate. He would have lost HW with a loss of cold water pressure to the boiler but not the CH
That is the case with mine. The boiler is on the outer wall of the attached garage. To get to the kitchen tap, the water runs from the boiler up the outer garage wall, across the roof of the garage, along the inner garage wall into the downstairs cloakroom, up from there into the bathroom, around the walls of the bathroom, down alongside the internal soil pipe to below the kitchen floor, across the kitchen floor and up to the kitchen sink! It does take a while to get there - but my bills are still considerably lower than they were under the old 'cylinder' system. I take your point over the improved efficiency of the condensing boiler however. It does, however, make great sense to just heat water as and when you need it - rather than heating up gallons of stored hot water which may never be used.
If someone else turns on a hot tap while I'm in the shower, there is a definite drop in water supply. This doesn't seem to happen if a cold tap is turned on, so perhaps my water pressure is sufficiently high to overcome this.
I accept that there are some downsides to even the best combis - but although I had some concerns about switching to a combi system, our experience over the two years since we switched has not given us any reason to regret our decision. Being able to get rid of the space wasting airing cupboard in the bathroom, and install a 'proper' shower cubicle is certainly one of the major advantages. The pressure and flow from the shower is really good as well - no need for pumped 'power showers'.
Were TRVs fitted with the new boiler or did you already have them? I am asking as I believe fitting TRVs can make as big a saving as changing a boiler.
My washing machine is not an A rated cold feed only version and so will draw hot water. That is when my shower splutters slightly. But I am not changing the washer as it still works fine. I doubt that changing a 10 year old washing machine for a new energy efficient one will save the enviroment. It certainly will not save my bank balance.
We would not have alternatives if something was perfect for everyone. I actually have made provision to allow for a HW tank in the loft if I ever needed one and still keep my combi boiler (ie I get married and have kids etc).
I already had TRV's fitted. I installed them myself some years ago.
True enough!
My neighbour had an identical boiler to mine (WB 30 CDi) installed when they had a bedroom/en-suite extension added to their house. They have found that it is a problem if they have guests and are trying to run showers in the new en-suite and the 'old' bathroom at the same time. I can accept that combis will not be ideal for everyone.
The drop will be down to the new boiler. Personally if I haven't used the whole cylinder full of water on one day I keep it and use it the next day. It seems a waste to throw it away. Having insulation on the cylinder seems a good idea.
I have a tank. It's adequate to feed two pumped showers simultaneously. No combi could do that. Although of course with a combi you don't need a pump or a tank!
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