I don't follow you, sweetheart. We had low pressure at all the hot taps, good pressure on the cold. After adjustment of the diaphragm thingie on the hw cylinder inlet, we now have good pressure on all hot taps. OK darling?
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Exactly sweetie, I *don't* have a hot water cylinder, hot water is supplied on demand by being heated as the cold water flows through the boiler. If it flows flowly enough to be heated to a useful temparture, it's flowing too slowly for a decent shower. If it's flowing fast enough for a decent shower, it's flowing through the boiler too fast for it to be heated up, escpecially now that the cold supply arrives at 8 degrees since the snow stared. This is why I hate non-stored hot water systems.
JGH
That's the first time I've heard of a 'combi' system. Sometimes posting to uk.d-i-y from NZ does make a difference.
Not neccessarily. At my old place I had a combi boiler with hot water cylinder. I specifically specified keeping the cylinder when the old boiler was replaced specifically to avoid the crapness we've been discussing.
JGH
combis dont have hot water tanks
with luck, it will be the last as well.
spawn of the devil.
A combi is to what we used to call a 'geyser' as a wimnd turbione is to a traditional windmill.
I.e. a really crap idea dressed up in modern clothes and sold on the basis that it actually does something useful after all.
The only 'combi' I have used that really worked for hot water, was the one my sister had in germany. It lived in the basement and was the size of a family car. That actually could produce a hot shower.
Sometimes posting
Then why did you bother with a combi boiler?
My combi based installation has a couple of valves in the loft that can be crudely used to adjust flow. The hot one suffered from the washer swelling and restricting the flow.
I'm amazed dribble hasn't been here yet. ;-)
Don't some store a small amount of hot water to get over the initial wait from those without?
No reason why you couldn't heat a cylinder from a combi. And keep the 'instant' feature for the kitchen tap.
"Dave. ;-)
My Worcester Heatslave floor standing one had this feature - the problem was though that the stored water was hotter than what the boiler could produce for a shower which meant that the shower started off really hot using the stored water and then got a bit cooler. However - never a big problem - more one of it being too hot to start with.
It's a TMV and comes factory set to a (low) maximum temperature (43 deg or so typically) which is low enough not to cause scalding to elderly or disabled people if installed in a care home or such. The idea is the makers don't get sued when a numpty plumber causes scalding to someone's granny. You can alter the maximum temperature, usually involves taking knobs off and such. See manufacturer's installation instructions.
No, ignore that. You've done it.
probably unequal pressures or a defective cartridge.
No reason why you would install a combi with hot water storage.
The reason combis exist, is that the cost of a combi is less than a conventional lower powered boiler plus hot water tank, plus shower pump plus header tank.
Or less than a conenvtional boiler plus mains pressure tank.
Once you start adding heat banks or a cylinder to a combi, to make it work better, the cost then exceeds a conventional boiler and mains pressure tank.
Not a lot of point doing that, you just need to insulate the tank and pipes and use a non combi bolier. A hot water cylinder is just a dedicated heat store and has the same advantages (unless its a bungaloo).
That's not very hot either. It there a thermostat on the boiler that controls the outlet temperature? What is the boiler's rated power? Robert
There's no cylinder, that's what's annoying. I'm used to a cylinder with 25 gallons of hot water sitting there waiting for me to use it at any time, not waiting for a boiler to suddenly wake up and desperately try to heat the water as it rushes past it.
That might do it. I'll have a chat with the landlord (or see if I can find it myself).
Ah! Are you in Scotland by any chance? It's possible that there's been a thermostatic mixing valve installed somewhere (that pre-dates the present shower control valve) that's restricting maximum HW temp.
Tim
There's no cylinder, that's what's annoying. I'm used to a cylinder with 25 gallons of hot water sitting there waiting for me to use it at any time, not waiting for a boiler to suddenly wake up and desperately try to heat the water as it rushes past it.
That might do it. I'll have a chat with the landlord (or see if I can find it myself).
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Are you in Scotland by any chance? It's possible that there's been a thermostatic mixing valve installed somewhere (that pre-dates the present shower control valve) that's restricting maximum HW temp.
Tim
messagenews: snipped-for-privacy@davenoise.co.uk...
Interesting - I've yet to find a combi supplied kitchen tap that was 'instant'.
I have a traditional system, and get hot water through in reasonable time and with good flow - I think every house I've been into in which the hot water is combi supplied, the wait has been extensive and the flow weak. Rob
messagenews: snipped-for-privacy@davenoise.co.uk...
Correct.
You need something like a 50KW combi to heat hot water really fast.
Which then needs to run at much less to do CH. Which is why the better designs modulate down. But even so, efficiency is poor.
And the requrements are quite different as well. Optimal outflow for modern radiators in not freezing temps might be as low as 35-40C.
Optimum hot water as far as I am concerned is 60C or so.
Google for E-on showersave. They were doing a promo with Anglian Water where they were sending these out free. Fits in line with the shower hose or shower head and limits the flow rate to around 9l/min.
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