DHW SETTINGS on Gas Boiler

Jon999 · Nov 25, 2022

Why are there options for setting time periods for DHW?

If set for 24hours, ie 24/7 won’t the boiler simply turn on .. on demand?…no need for time periods!

What am I not seeing?

Deleted member 120897 · Nov 25, 2022

What we’re not seeing is what type of boiler/system you have 😂😂😂😂

Jon999 · Nov 26, 2022

ChrisB1982 said:
What we’re not seeing is what type of boiler/system you have 😂😂😂😂

Sorry….I thought all CH systems were generally the same!
NG - Worcester GREENSTAR 8000 life CH-15Rads/DHW

Chuck · Nov 26, 2022

If you have the DHW on 24/7 the boiler will try to keep the tank at 60°C all the time which means the return temperature from the heat exchanger in the tank will be at 60°C, which is inefficient, and there will be unnecessary wear and tear on the zone valve and boiler. Also, having the boiler cycling on and off can be annoying to occupants, particularly at night, due to noise.

Jon999 · Nov 26, 2022

Chuck said:
If you have the DHW on 24/7 the boiler will try to keep the tank at 60°C all the time which means the return temperature from the heat exchanger in the tank will be at 60°C, which is inefficient, and there will be unnecessary wear and tear on the zone valve and boiler. Also, having the boiler cycling on and off can be annoying to occupants, particularly at night, due to noise.

If DHW is programmed for set periods of on and off and a demand for dhw is made during an off period presumably there will be a delay in obtaining hot water, whereas if this happened during on period, hot water demand would be effectively instant!

Chuck · Nov 26, 2022

Jon999 said:
If DHW is programmed for set periods of on and off and a demand for dhw is made during an off period presumably there will be a delay in obtaining hot water, whereas if this happened during on period, hot water demand would be effectively instant!

Sorry, my reply was written with a system boiler and external DHW store in mind. If you have a combi and are talking about scheduling the 'preheat' function then things are a bit less extreme but you are still trading off energy use against convenience and potentially wasted water.