Tap water too hot from combi

Tap water too hot from combi

Author
Discussion

driverrob

Original Poster:

4,692 posts

204 months

Saturday 2nd December 2017
quotequote all
We have a Worcester Bosch combi boiler Greenstar 29CDi Classic LPG. It's 3 years old but I can't be sure how long we've had the problem.
I originally set the tap water temp at 5, then 4, then 3 and it was still uncomfortably hot for my hands. Yesterday I turned it down to minimum (1) and it has made no difference. Turning on 'Eco' just means it takes longer to get to that temp.
Could this be something easy to adjust or does the boiler have a fault?
It was serviced a few weeks ago. The guy commented on the setting but that's all.

RHVW

139 posts

78 months

Saturday 2nd December 2017
quotequote all
Temp to min and flow rate to max

Fore Left

1,423 posts

183 months

Saturday 2nd December 2017
quotequote all
Turn the cold tap on? thumbup

I thought water should be at least 60 degrees to stop legionella.

Alucidnation

16,810 posts

171 months

Saturday 2nd December 2017
quotequote all
Only for open vented.

robbieduncan

1,981 posts

237 months

Saturday 2nd December 2017
quotequote all
We have an unvented system. The water coming out of the storage tank was too hot (especially for small children). Water has to be stored at high temperature so reducing that was not an option. We opted to have thermostatic mixers added under every sink that limits the maximum temperature to something more reasonable

Wiccan of Darkness

1,847 posts

84 months

Saturday 2nd December 2017
quotequote all
Had the same issue with my Worcester bosch, deffo sounds like a thermostat issue. The water continues to heat up and doesn't stop when it's at the required temp, just keeps on heating.

On the side of the hot water tank, there's a thermostat. Mine had simply been wedged in to the insulating foam and it had fallen out. It sits on the side of the tank so the system knows how hot the juice is in the tank. Check yours hasn't fallen off. I stuffed mine in to the foam and duct taped it in place, job jobbed.

If not, then the thermostat is probably buggered.

Edit. I've just looked at the hot water tank and the thermostat on the side of the tank has a screw on it, with temperature settings. Use a flat head screwdriver to turn that to make the water hotter or colder. The twiddly knob on the boiler itself I'm sure is the intensity of the burn - set it to 5 to heat the water faster. The thingy on the tank is for the temperature of the water.

Have a look on the side of the hot water tank itself, not the boiler, and check to see if there's an adjustable thermostat on that. You're looking for a 3" x 2" box with a decent sized mains cable running from it, actually on the side of the tank itself.

I'm thinking your 1-5 settings are the speed at which it heats the water and nothing to do with final temperature.

eldar

21,858 posts

197 months

Saturday 2nd December 2017
quotequote all
Wiccan of Darkness said:
Had the same issue with my Worcester bosch, deffo sounds like a thermostat issue. The water continues to heat up and doesn't stop when it's at the required temp, just keeps on heating.

On the side of the hot water tank, there's a thermostat. Mine had simply been wedged in to the insulating foam and it had fallen out. It sits on the side of the tank so the system knows how hot the juice is in the tank. Check yours hasn't fallen off. I stuffed mine in to the foam and duct taped it in place, job jobbed.

If not, then the thermostat is probably buggered.

Edit. I've just looked at the hot water tank and the thermostat on the side of the tank has a screw on it, with temperature settings. Use a flat head screwdriver to turn that to make the water hotter or colder. The twiddly knob on the boiler itself I'm sure is the intensity of the burn - set it to 5 to heat the water faster. The thingy on the tank is for the temperature of the water.

Have a look on the side of the hot water tank itself, not the boiler, and check to see if there's an adjustable thermostat on that. You're looking for a 3" x 2" box with a decent sized mains cable running from it, actually on the side of the tank itself.

I'm thinking your 1-5 settings are the speed at which it heats the water and nothing to do with final temperature.
The OP has a combi boiler, so no tank.

Sheepshanks

32,887 posts

120 months

Saturday 2nd December 2017
quotequote all
driverrob said:
Could this be something easy to adjust or does the boiler have a fault?
If you fully open a hot tap, how long does it take to fill a 2 gall / 10 litre bucket?

And same with cold water only.

driverrob

Original Poster:

4,692 posts

204 months

Sunday 3rd December 2017
quotequote all
The pressure is not brilliant here c. 1.5 bar at the boiler. We're fairly high up and I'm pretty sure it's 1/2" feed from the road. But within limits, the water board say.
There is (was) a 5 year warranty on the boiler and we have a yearly inspection so I'm wondering if I should contact the manufacturer or the service company or just accept it because that's what it's supposed to do. I know there are some knowledgeable PHers in this area.