Boiler temperature?

[thighofrelief]

Had a gas safety check recently and we've been boiling even without the heating on and the water is too hot. Just checked the boiler and it says optimum flow temperature 65c so I changed it to 40c. Anyone know what it should be please?

My crystal ball tells me that you have a modern condensing boiler. However it doesn't tell me if you have a combi or a hot water cylinder.

I wonder if your radiators are warm.

piglet thanks it is not a combi, the radiators are not warm but the floor in my bedroom (where the water tank is) are warm

I've just had a new boiler fitted and like you found the water temperature hotter then needed. Looking in the operating instruction booklet it says "Danger risk of death from legionella". Legionella multiply at temperatures below 60c.

It is a valliant ecotech plus 618

My one's a Vaillant ecotech pro.

Bugger, will have to call out the gas man on Monday. I hoped it was something easy like setting a temperature. Vitalogy - did you adjust it yourself?

Well, I was going to until I read the legionella info, so I'm going to leave it as is.

Can't you just set it back to 65c. I know it could be a worry if you have young children with how hot it can get.

I don't think there has been a case of Legionella reported in domestic boiler setting.

I could set it back to 65 but we are so boiling, windows open and ceiling fan on.

"piglet thanks it is not a combi, the radiators are not warm but the floor in my bedroom (where the water tank is) are warm"

So if the radiators are not warm, why is the house hot? How is the cylinder insulated? Or is the sun shining?

It is not unusual to find that where pipes pass under a floor, that section of the floor will be warm, during the time the cylinder is being heated (unlikely to take as long as an hour)

btw the Legionella temperatures are not as high as is sometimes said.

A temperature of 60C will kill it, and a temperature of 45C or higher will prevent it multiplying. It is happiest round about body temperature.

65C will kill it more quickly. But the water in your hot water cylinder is likely to be stored at 50C to 60C for long periods, so unlikely to support life or breeding.

You would do better to ensure that the cold-water tank in your loft is clean, and has a tight-fitting lid and an insulating jacket. Lofts can get very warm on sunny days.

More details on www.hse.gov.uk/healthservices/legionella.htm

The temperature requirement is actually from the Water Supply (Water Fittings) Regulations 1999. The HSE information about Legionella comes from there. The legal requirement is for hot water to be stored not less than 60c. There are cases of Legionella in domestic properties, we deal with them every day, that's why domestic rented properties have required Legionella Risk Assessments since 2013. If you have had a gas safety check but don't have a combi then you have a system boiler which will heat a store of hot water through a coil in your immersion heater as well as your heating when required. The pipework will run under floors etc and sounds like it isn't insulated, it has the effect of underfloor heating. Buy some pipe insulation from a DIY shop and insulate as much of the pipework as you can to minimise the effect. You could also have a faulty 2 or 3 port valve allowing hot water in your heating pipework even when there is no heating requirement.

If the boiler is running for long periods it could be that the heating water temperature is lower than the set temperature of the water tank.
You should ensure the water tank is at 60 and the boiler should be at least 65 when heating the water tank.
Also, the pipes that lead to the cylinder should be insulated with regulations compliant levels of insulation. There shouldn't be any exposed metal either under the floor or around the water tank.

Thank you all for trying to help but I'm going to get the gasman back asap. We were fine before the safety check and he was only here 5 minutes. I don't want to risk blowing us up or legionella