Advice please! Combi v 'thermal store'

Cardew

I am no plumber, but if you have little pressure in the upstairs taps now, you may find this is a bigger problem with any future plumbing work as smaller diameter pipes and different style taps are used.

I had exactly this problem with a bathroom refit - the low pressure/flow in my taps made water saving easy - cos nothing came out!

The surprisingly easy solution was to fit a pump. This pump is demand driven and has turned one of our showers into almost a 'power shower'. They can pump either hot or cold or both. We now have an excellent flow. There is a thread about this on MSE

Incidentally a scoring point(for your wife's benefit) is that the £100 loss from the tank, isn't really a loss as the heat goes into the fabric of the house; which is useful 9 months of the year.

Uzima

Thanks Cardew, yet another option! I wish I had all this hands-on experience. The cistern, if we keep one, needs to be fairly large as I understand it. I don't know what the regulations require. But I see that there are combination cylinders with a header incorporated - some even have two headers, so one can serve as F & E. So we could replace the current cylinder with something like an indirect Fortic; go fully pumped on the primary circuit - without interrupting the vent pipe; and then pump the hot water out of the cylinder. All our upstairs cold taps are off the mains anyway, so pressure not an issue there. I was looking at Stuart Turner monsoon negative head pumps... they are pricey. Are they quiet? Do they last?

Cardew

Uzima,
These are the links:

http://forums.moneysavingexpert.com/showthread.html?t=316778&page=2 (read from page 1 first)

http://forums.moneysavingexpert.com/showthread.html?t=676935&highlight=pump+power+shower+pressure


I was worried that there might be noise and vibration but the mounts and anti- vibration couplings work well.

Uzima

Thanks Cardew. Very interesting, and good to have your experience of this as a solution - one of the two threads you listed ran over more than 18 months!

A pump would be my cheapest option. With a single Salamander pump for HW only - £200+ - and a combination cylinder for £300+. The pump could sit on the floor of the airing cupboard on a fused spur.

Adding a (further) pump to the primary circuit is something I have to do anyway, if we are not risking an investment in a combi. That 'only' needs pipework, bit of wiring and a new programmer, and either a motorised valve - or a Grundfos twin pump which can do the whole job. At least we can make a decision knowing these are feasible options. If an engineer comes in and tells me I need a sealed cylinder or a combi, we can have a discussion about it!

pennineman

We have a combi: Worcestor 28CDi. Now around 10 years old I think.

Sits in the bathroom airing cupboard.

Is horrendously noisy because sits on a wall which acts as a sounding board and magnifies sound - so noise can be an issue if you're unlucky.

Plus, in summer when CH is off it takes up to maybe 30 seconds before warm water flows instead of cold. I shudder at the waste of water involved here.

However, I suppose, it does encourage washing hands / rinsing dishes etc always in cold water - pointless firing up the boiler and then turning the tap off before the hot water has reached it!

Re maintenance - is serviced once a year as all our gas heating applicances are. Only recently had first non-scheduled work needing doing. A leaking heat exchanger which needed replacing. So over 10 years I thought this was fair.

Uzima

Ten year life seems a good advert for Wordcester Bosch, as far as combis go. We're lucky at least that our boiler location is on wall of ground floor extension far from the living/ sleeping place (though this means venting is not ideal - another story). If we do fit a pump on the hot water, as Cardew suggested, it will be in the airing cupboard near the bedrooms - but then so will the pump/s for CH and primary water, because we can't fit them at the boiler. But the Grundfos pump we have on CH now doesn't make much noise.

I agree about the water saving - we have a meter, which helps us concentrate on reducing consumption. I realise that what we do in summer is wash dishes etc with unheated water, but we still use the hot water tap at the sink, not the cold. This water comes from the cylinder and is at house temperature, which is quite reasonable in summer. Mains tap would be colder. And if we had a combi, turning on the hot water tap would presumably fire up the boiler anyway! Hmmm.

As a matter if interest, how much have you paid for your annual services to the boiler over the ten years? I'm afraid regular servicing is an unknown to us.

pennineman

Uzima wrote: »

As a matter if interest, how much have you paid for your annual services to the boiler over the ten years? I'm afraid regular servicing is an unknown to us.

Around £400 over the 10 years I'd guess.

Uzima

Thanks to everyone for their help. It's brilliant that members are prepared to set aside time to share their experience and knowledge in this forum. I am pricing alternatives, and finding out whether any local plumbers are prepared to entertain what we want to do! I'll post the result, though I know by then everyone will have moved on to more interesting fare.

I think we have confirmed that we won't be fitting a combi.

Cardew

Where is local?

Members might know a good plumber in the area.

Uzima

Thanks Cardew, if you are still watching! Just returned to the thread - yes, I would love to know if any local plumbers of good repute are prepared to be flexible! I am looking to get two or three quotes: Oxford-Woodstock area.