Combi or not combi - help!

[Dave Plowman (News)]

I have gravity hot water and no shower pump. And my shower is excellent. But as with taps and pipework, has to be designed for lower pressure, which most of the imported cheap stuff isn't.

[Andy Burns]

I've found Salamander pretty decent, not a peep of a problem from mine since 2009

[newshound]

Just saw them when checking ST prices. They do look reputable, just avoid Screwfix type entry level. I have seen three failures (two leaks, one electrical iirc) in this general type.

BES have a Salamander regenerative for less than £150

I guess it may be plastic rather than brass. The metal body gives you more secure support for the bearings and seal. There seem to be decent Grundfos too.

[John Rumm]

Average showers are targeted to deliver typically from 8 lpm these days.

15 lpm would be on the higher end for a normal shower mixer.

Most modern (decent) system boilers have modulation anyway. Typically the higher powered combis don't output the same power to the CH side either. (my old 35kW Ideal Isar only delivered a maximum of 25kW to the heating side).

Even a 35kW combi will feed two showers at once. Not as well as it will do one, but still each will be better than an electric shower for example.

I agree its a good system (its what I installed here). However it has some of the same limitations as a combi. If you mains supply pressure or flow rate is inadequate, then neither system will work well.

Not convinced. If you compare like with like kit there is not much difference in price. If installing yourself so you don't need to cost the labour, then there is not much in it. If paying for the installation, then (depending on the starting situation) there may be a fair amount of extra work for an unvented system.

That rather depends on your peak demand. The last combi I fitted was for a place with one shower and no bath. (With no ideal location where a cylinder could go). The 24kW combi met the peak demand with ease.

That's not much cheaper than unvented by the time you add the cost of a cistern even if the cylinder itself is a bit cheaper. However its better suited to properties with low mains flow rates.

I also have experience of a variety of styles of system. However do not find it so easy to make blanket Dr. Dribble style assertions. One needs to look at the bigger picture.

[Vir Campestris]

Point of information - only if the shower is upstairs. There's enough head from a loft tank on the "2nd floor" to feed a shower on the ground quite effectively.

Andy

[Dave Plowman (News)]

It does also depend on the pipework design as to how much restriction there is. With a low head, you have to take much more care.