Worcester 24 DCi pressure/hot water requirement

[Zeissman]

Hi all,

I am really struggling to get to grips with a Worcester 24 DCi and I'm pretty sure that it's mocking me.

I have to turn on two hot water taps at any time to get the boiler to recognise that it needs to create hot water.

Once this happens, the water is only luke warm, possibly because the flow rate must be quite high (we live in quite a high pressure area anyway).

I would really like to have a hot shower too but again, it's a choice of less pressure and freezing cold or very high pressure (as in shower head becoming detached from the wall and flailing all over the bathroom) and luke warm. :banghead:


The pressure in the boiler keeps dropping slowly too but this may not be related as it's a new issue and I am sure that it is just a leaky connection in the radiator system somewhere. Any help would be VERY gratefully received.

Z.

 

[grahamgas]

When running the hot water, check the heating flow pipe to see if the diverter valve is faulty. A 24 kw boiler is normally only good for 10 litres per minute, at a 35 degree celsius rise. So, if you have 15 litres a minute going through, your heat rise is going to be less.

 

[mylesy]

24 CDi or 24i junior?? sounds like you should have had a boiler that can handle more hot water! it should fire when only as little as 1 liter is flowing. also they generally have a flow restrictor built in but you can close the valve at the boiler slowly whilst holding a weir gauge under a tap until you get 9 ltr/min with a tap fully open. is it new?

 

[Zeissman]

When running the hot water, check the heating flow pipe to see if the diverter valve is faulty. A 24 kw boiler is normally only good for 10 litres per minute, at a 35 degree celsius rise. So, if you have 15 litres a minute going through, your heat rise is going to be less.

Thanks grahamgas, annoyingly, yes, the CH flow pipe does become warm. I hadn't noticed before because the temperature difference was so minimal!

Would this explain why so much water flow is required to notify the boiler of demand? The DHW demand light used to kick in as soon as I touched the tap but now it takes a river running through the bathroom!

 

[mylesy]

nice call with the diverter! i was thinking flow turbine, but didnt know age of boiler.

When running the hot water, check the heating flow pipe to see if the diverter valve is faulty. A 24 kw boiler is normally only good for 10 litres per minute, at a 35 degree celsius rise. So, if you have 15 litres a minute going through, your heat rise is going to be less.

 

[Zeissman]

24 CDi or 24i junior?? sounds like you should have had a boiler that can handle more hot water! it should fire when only as little as 1 liter is flowing. also they generally have a flow restrictor built in but you can close the valve at the boiler slowly whilst holding a weir gauge under a tap until you get 9 ltr/min with a tap fully open. is it new?

Thanks mylesy, it's definitely a CDi and is probably 10 years old. Normally, I don't need to heat anywhere near 10 litres/min. In fact, it can get pretty painful in the shower now that I have to turn it up! I've tried adjusting (temporarily) the mains cold flow rate by being delicate with the stop-cock which is right next to the boiler but the boiler is still not recognising the demand for DHW unless two taps are open, and now they both need to be fully open.

 

[mylesy]

i think grahamgas is right with the diverter. maybe the diaphrgm isnt sensing the hot water with the venturi principal. also it sounds like your getting central heating temperatures to your hot water. CH 82 degrees DHW around 55 (at the right flow rate) wonder if the thermisters are in range. id sort your valve out first and take it from there. it should realy fire quite soon. you can sometimes press the switch yourself with a screw driver on the valve whilst one tap is running just to see.

 

[diamondgas]

CAUTION! --- Not a job for someone inexperienced IMHO ... water water everywhere .... It does sound like the diaphragm I'd have to agree!

:welcome: to the forum

 

[jtsplumbing]

Think the first thing would be to fit a pressure reduceing valve, from what you are saying your pressure is way to high, not doing the boiler or any other items any good, get your press down to around 4 bar and you may solve your problem!!.

 

[arran197]

If it's the CDi I'm thinking of then it's likely to be the diaphragm, which is a complete and utter ball ache to change. You're best off changing the whole thing, although I did manage to change just the rubber on one. It did take me hours though!

 

[Zeissman]

Thank you very much everyone - seriously helpful! :clap:

Time to get someone in to fit the new diverter and pressure reducing valve. As diamondgas says, water water everywhere!