Boiler flow temperature regular boiler

Sterlingtimes

Grant Shapps would like everyone to turn their flow temperature down to 60 degrees.

I have a conventional condensing gravity-fed boiler. I do not think that the temperature reduction works for me.

I understand that a house has a "design flow temperature". What would the likely flow temperature be for a house newly built in 1995?

MACKEM99

Will Turing the boiler temp down not make the boiler have to work harder to heat the radiators to the required temperature?

thevilla

There's a ton off stuff on this on YouTube.  I think a flow temperature of 85 degrees used to be the norm.  Recently 55 has been specified for new installs.  If you heat hot water in a cylinder with your boiler then be careful as a low flow temp may not get the water to its specified temp.  In general low temperature allows more chance of a condenser boiler actually condensing and gaining efficiency.

1961Nick

50-55C on the return is what you're looking for. The flow would typically need to be between 65C & 75C to achieve that.

If you set the DHW temperature much below 60C, run a legionella cycle every couple of weeks by turning the tank stat up to 60-65C for a single 'event'.

Sterlingtimes

1961Nick said:

50-55C on the return is what you're looking for. The flow would typically need to be between 65C & 75C to achieve that.

If you set the DHW temperature much below 60C, run a legionella cycle every couple of weeks by turning the tank stat up to 60-65C for a single 'event'.

Thank you, Nick. That is the guidance that I required. I will try to find some way of measuring the return temperature.

The Grant Shapps one temperature suits all formula will not work here.

1961Nick

Sterlingtimes said:

1961Nick said:

50-55C on the return is what you're looking for. The flow would typically need to be between 65C & 75C to achieve that.

If you set the DHW temperature much below 60C, run a legionella cycle every couple of weeks by turning the tank stat up to 60-65C for a single 'event'.

Thank you, Nick. That is the guidance that I required. I will try to find some way of measuring the return temperature.

The Grant Shapps one temperature suits all formula will not work here.

Just noticed you signature - Using the immersion for a 65C top up after the boiler has heated the DHW would be ideal for a legionella cycle if that's easier. 

Sterlingtimes

thevilla said:

There's a ton off stuff on this on YouTube.  I think a flow temperature of 85 degrees used to be the norm.  Recently 55 has been specified for new installs.  If you heat hot water in a cylinder with your boiler then be careful as a low flow temp may not get the water to its specified temp.  In general low temperature allows more chance of a condenser boiler actually condensing and gaining efficiency.

Thank you, thevilla, I am learning. My heat engineer contends that a blockage slows the flow close to where the cold water down feed from the expansion tank meets the pump. He is coming to reconfigure the pipework and fit an air separator and a new pump (which is "no spring chicken", according to the plumber). Perhaps these modifications will give me some latitude to reduce flow temperature, but at the moment, 70 degrees looks like the happy point. 

Screwdriva

Bottom line in my humble experience: it comes down to your property's heat loss and your personal comfort level. Our home was built in 1990, which means that we both likely have (better than average UK stock) uninsulated post 1983 cavity walls.

Prior to our recent efficiency retrofit, we were in a similar position and did everything listed in this thread to achieve a 25% reduction in gas consumption last winter. Reducing our old Worcester Bosch's flow temperature to 55 degrees had the biggest impact on this. It meant warm (not hot) radiators, which took getting used to, but at no point did we feel uncomfortable. I'd suggest starting there. If you find the house too cold, turn it up one degree every few hours till you get to where you are happy. Conversely, test this new flow temperature by lowering it by one degree the next cold day to see how you feel. If comfortable, leave it there and try again till you settle at a temperature. 

Upgrading our boiler to the Viessmann 200-W, installing underfloor heating and a few other improvements have reduced consumption by approximately 40% over and above the previous savings, effectively negating most of the increases in gas prices for us. This was a most unexpected (& pleasant) result! We continue to monitor to ensure these savings aren't diminished in current colder weather.