Boiler Hot Water Output

[BigBurner]

My plumber came back this morning and said the gas pressure is now working fine. But there is still the problem that I only get hot water when I turn the kitchen sink on full (hot water is fine when I turn the tap half way when the heating is on) and I get luke warm water when both showers are on simultaneously. He assures me that these are faults and the boiler should produce hot water when I turn the tap on half way and there should be no drop in temperature or pressure when I use two showers at once. So he has called Worcester and they believe that there may be a problem with the diverter valve or heat exchanger and they are coming on Thursday.

He did point point out that at the boiler, the incoming mains is 15'C cooler than what Worcester recommend but he said this should not cause the issue of me having to turn the sink tap on fully to get hot water (it's freezing cold unless I turn the tap all the way).

This could have been gas mains distribution problem (maybe now fixed) or a sticking regulator and may re-occur. The Transco man was wrong, it was regulator/distribution problem.

15C cooler? What does that mean? It is probably between 7C and 10C incoming. That means 20 litres/min flow at 42C to 45C tap temperature.

Once working properly you will not be disappointed. I hope he put pressure equalisers on the showers and balanced the hot and cold water system. A dishwasher does not need full flow, a shower does.

 

[Agile]

He did point point out that at the boiler, the incoming mains is 15'C cooler than what Worcester recommend but he said this should not cause the issue of me having to turn the sink tap on fully to get hot water (it's freezing cold unless I turn the tap all the way).

I doubt that he really said that!

Mains water at the moment is about 4-6°C but rises in the summer to about 14-16°C.

Worcester boilers can manage incoming water from 1°C to 25°C

Tony

 

[Maxx470]

Thank goodness for oil heating !.

 

[pototea]

He did point point out that at the boiler, the incoming mains is 15'C cooler than what Worcester recommend but he said this should not cause the issue of me having to turn the sink tap on fully to get hot water (it's freezing cold unless I turn the tap all the way).

I doubt that he really said that!

Mains water at the moment is about 4-6°C but rises in the summer to about 14-16°C.

Worcester boilers can manage incoming water from 1°C to 25°C

Tony

I must have misheard him on the phone! I'll wait until Worcester have been out before asking him to clarify.

The Worcester 440Cdi I have is the newer model with 25litres/min output BUT I remember him saying awhile ago that this relies on a certain input temperature which was ridiculously high, I don't remember the exact figure.

 

[BigBurner]

The Worcester 440Cdi I have is the newer model with 25litres/min output BUT I remember him saying awhile ago that this relies on a certain input temperature which was ridiculously high, I don't remember the exact figure.

The 440 is 20 litres/min. The 550 is 25. They are rates at 35c temp rise. 10C mains temp and 45C at the taps at 20 litres/min. If 15C inlet then 50C at the taps, or reduce the temp and get more flow.

 

[pototea]

I don't suppose anyone can comment based on average conditions if I can expect two hot showers simultaneously from this boiler as my plumber thinks or when Worcester come, are they likely to say it can only run one shower at a time?

The fact that I only get hot water from the sink if I turn the tap on fully does seem to indicate a diverter valve problem as I had the same problem on my Potterton but I would just like some feedback from other experienced Worcester users (it's fine when the heating is on and I can turn the tap half way and get hot water).

Thank god I got it confirmed in writing frmo them that they would support boiler installation in the loft!

 

[gas4you]

Whats your cold mains pressure like?

By the time it reaches your boiler in the loft it will have dropped at least 0.6 Bar.

If the cold mains is not too good then this could be enough to not trigger the HW demand properly, as in your old Potterton, unless the tap is turned on full.

As these are designed to be floor standing, downstairs usually, I would look into this aspect more closely

 

[pototea]

Pressure was 4 bar and 12 litre/min off my old lead piping. That has now been upgraded to 28mm piping so should be greater (it certainly feels a lot more powerful, the shower nearly flies off the wall now!).

The same problem I experienced with my Potterton WAS the diverter valve. Getting that replaced fixed the problem. Given that this Worcester is brand new and only installed last week, I am surprised about the lack of hot water and am wondering if it is a fault or it is supposed to behave like this given the setup.

 

[gas4you]

28mm should hopefully increase flow, but not the pressure.