Combi boiler question for boiler engineers

[stuartwatts]

A quick question for any boiler engineer's:

Why do some combi's have a diverter valve and some have a flow switch AND a diverter valve? what's the difference/advantage? I am moving into a new flat soon and it has a combi boiler, which I have never had before, but I've heard different opinions about them - and wondered what the difference was!

I know some use just a flow seitch for the hot water (twinflow type I believe)...


Many thanks for your help

Stu

 

[petit_pablo]

Just depends on which type of diverter the manufacturer specs in the boiler.

"older" style combi's tended to have a diverter that incorporated a pressure differential valve to sense hot water demand. The whole process of ensing water flow and moving the valve was mechanical. Less complicated electronics and cheaper parts generally using this method. Downside was the constant wearing of the pressure differential diaphragms and the valves stick causing heated water to "pass" the valve.

"newer" style combi's almost all use a flow switch of some form and an electronically operated diverter valve. Tends to be a more reliable setup as many diverters are pushed and pulled into position by a motor rather than relying on springs. Not really a downside but in a HW fault condition, pressure differential valves were easier to fault find than the modern flow switch.

 

[Beerlover]

All combis have a flow detection device; beit a diapragm, turbine or reed switch.

Most have diverter valves, with only a few having twin waterways in the main heat exchanger (Bi-thermal).

Why do you ask?

 

[gasafengineer]

All good info..........................some of the older type combis ie: vaillant sine 18 used a wax capsule type divertor valve , some others used the venturi type , many ways to skin a cat as they say.

 

[Beerlover]

forgot about them

And the Potty Pumas

 

[stuartwatts]

Just wondered if they would be reliable

Thanks for all of your help and info i appreciate it.

Apparantly the flat has no heating control, only on when seletced manually at the boiler, no thermostat on the wall, etc - is there any good thermostat that I could get fitted for when the winter comes, to make it more efficient/easy to use. I wouldn't mind paying a decent price for a reliable one, and for someone to come and fit it for me nearer the time

 

[petit_pablo]

Do you know which boiler it is?

The honeywell wireless controllers are always well recommended on here.

 

[PlumbGas]

Do you know which boiler it is?

The honeywell wireless controllers are always well recommended on here.

couldn't agree more, I've got the 927 honeywell, wireless easy to operate for all and cheap to fit, lovely bit of kit,

 

[stuartwatts]

I have just found out it is a worcester bosch junior - not sure how old, but heard it is non condensing, so am presuming it is older....

Would I be able to wire one in myself? I have wired in ceiling roses and repaired flex's before, and also wired in an immersion heater thermostat when my old one went a few years ago.

Thanks for your help

How much is a Honeywell 927 approx?

 

[petit_pablo]

WB junior will be easy enough to wire a stat into. I dare say someone on here will help if you need a few pointers.

Incidently the WB junior is a dual pass heat exchnager. It has a flow switch and no diverter.

 

[stuartwatts]

Thanks I'll look at the manual.

Do screwfix do Honeywell 927's?

 

[PlumbGas]

Thanks I'll look at the manual.

Do screwfix do Honeywell 927's?

Try this site, middle of the link page you'll find the 927 http://www.bes.co.uk/products/112.asp