Hot water far to hot!

[Mark Hawkins]

I have a very old potterton kingfisher floor mounted boiler running pumped ch and gravity hot water...

Regularly serviced and seems to run well. Problem is the hot water seems to be to hot.

My son was over the other day and was shocked at the temperature, so I checked it out and it was 82 deg. Boiler stat was on 3, so I turned the boiler down to 1 and checked again after a day, was now at 75.. I've since wound it down to 'min' and it's now at 72, better but still not right! Now the heating takes an age to get temp up from its hold temp to comfort.

I think this has always been the case but I realise now it's not ideal and it could lead to other issues such as failed pumps and limescaled tanks.. And I have recently fitted a aqualisa Quartz shower!!

How can I get the temp further down please?

 

[bill2013]

Check to see if the thermostat on the hot water cylinder is set at 60deg.If its not,set it to that temp.If that dose not work then you need a new cylinder stat.

 

[shambolic]

Check you haven't put on your electric immerser by accident.

 

[shambolic]

Check to see if the thermostat on the hot water cylinder is set at 60deg.If its not,set it to that temp.If that dose not work then you need a new cylinder stat.

Eh no it doesn't as boiler stat at lowest settings would only ever give out, depending on boiler 30-40deg max. So it wouldn't matter if cylinder stat was at 100deg.
It would never get to that temp if boiler stat ok.
Ours go from min(32) to max(80).

 

[Mark Hawkins]

Okay, have checked immersion heater that is off. And yes, there is no cylinder stat on this system.. I think temperature at the cylinder is controlled by the boiler stat.. ie, the hotter the water from the boiler the hotter the water in the cylinder

 

[bill2013]

There must have been some way to control the hot water temp. There could be a Cytrol valve on the return from the cylinder.These are adjustable but are likely to leak after adjustment.

 

[Hugh Jaleak]

Not a vast amount you can do as is, ideally you need to look at adding further controls to the system. Honeywell 'C' plan is probably the easiest option, although the system will then need upgrading to fully pumped in future in the event of a new boiler being fitted.

Early systems were gravity only, for HW and CH, then with the advent of pumps, the CH became pumped, allowing small bore pipework to be used for the radiators. The gravity primaries from boiler to cylinder still remained minimum 1" pipework, and no controls were fitted, other than a time clock to switch the boiler on/off. HW temp was controlled by the boiler stat, and often got dangerously hot.

Building regs now require more control and with the use of motorised valves, fully pumped systems became the norm.

 

[Mark Hawkins]

There must have been some way to control the hot water temp. There could be a Cytrol valve on the return from the cylinder.These are adjustable but are likely to leak after adjustment.

I see what you mean but will this not just slow the process of ultimately reaching the max temp set by the boiler stat

 

[Mark Hawkins]

Not a vast amount you can do as is, ideally you need to look at adding further controls to the system. Honeywell 'C' plan is probably the easiest option, although the system will then need upgrading to fully pumped in future in the event of a new boiler being fitted.

Early systems were gravity only, for HW and CH, then with the advent of pumps, the CH became pumped, allowing small bore pipework to be used for the radiators. The gravity primaries from boiler to cylinder still remained minimum 1" pipework, and no controls were fitted, other than a time clock to switch the boiler on/off. HW temp was controlled by the boiler stat, and often got dangerously hot.

Building regs now require more control and with the use of motorised valves, fully pumped systems became the norm.

Yes it's exactly that.. Works fine apart from HW temp, shame really. I think you're right in that it needs updating to at least 'C' plan... It would be nice to have more control, and to not be heating water 24/7 at the moment could make it cheaper to run!

 

[Hugh Jaleak]

Basically the Hot water in the cylinder will be same temp (eventually) as the water in the primary system, some 20° C (approx) higher than you need it to be. Once it reaches that temperature though, circulation around the primaries should cease, and the boiler output directed into the CH. However, its now a primitive method, and wasteful of heat and gas.

I dont think the C plan is a major job to retrofit, fit the valve on the primary return, and wiring alterations as required. It is imperative though the valve is fitted correctly, and there remains an open path from the boiler to the vent over the F&E cistern.

 

[shambolic]

But if his boiler is set to 32 ( setting 1 )then the hot water should never get above 32 FFS
So his boiler stat must be faulty or some other fault keeping gas on to heat boiler.
Or some external heat like immerser heating it( been ruled out)

 

[ServiceNumpty]

Sometimes dab of heat sink does wonders.

 

[Mark Hawkins]

But if his boiler is set to 32 ( setting 1 )then the hot water should never get above 32 FFS
So his boiler stat must be faulty or some other fault keeping gas on to heat boiler.
Or some external heat like immerser heating it( been ruled out)

So my old Potterton Kingfisher... Setting 'min' is 32 degrees water temp? How do you know this? turning it up and down does adjust the temperature so I would assume that the thermostat works?

 

[shambolic]

But is it right? Check online for your specific stat. Ours are 32-80 and I don't think potterton will be far off that.

 

[Steelmasons]

Stat range will be in the region 55 to 85c.
Minimum of 55c in order raise water temps above flue gas dew point , any lower then back end rot will shorten the old bruisers life span.