You may have seen the recent news about "Peak Time Usage Alerts" where the National Grid will be sending out test alerts on several occasions this Winter to gauge people's responses when asked to reduce electricity demand during Peak Hours of 4pm to 7pm.
For those of us who have homes fitted with Air Source Heat Pumps (or Ground Source Heat Pumps) there are three important settings to check that can seriously help with your Peak Time usage. In fact checking these settings will help all the National Grid all year round, not just on these High Demand days.
If your home is the more usual Gas Boiler for domestic hot water and space heating then these suggestions won't apply to you.
The first thing to check on your Heat Pump is the timer for when the hot water is allowed to be brought up to temperature in the afternoon. Heating water all the way to 50C is a heavy use of power. A bit of planning can shift this activity out of the Peak Time window. Make a note of how long it takes to top up your tank during any afternoon slot. Move the permitted time to enough before 4pm that it would be finished before 4pm rolls round and prohibit it from coming back on again until 7pm.
Next, check the timer for your heating circuit. Most Heat Pump systems will have some form of underfloor tubing and a (usually) concrete floor to store heat. This slab takes days to come up to temperature at the beginning of the Winter season but holds its heat very well. Since the underfloor water is only heated to low-30s C it does not demand as much electricity as the hot water tank but it is something that tends to be on for a long time. Change the Timer so that there is a dead spot in the Heating between 4pm and 7pm. Because of the warm slab you won't notice the missing few hours and it can easily catch up once the Peak has passed.
Finally check when the timer for the Legionella Cycle is permitted. This normally heats the hot water tank all the way to its maximum and then adds the Immersion Heater on the top too. It tends to run every two weeks. Absolutely make sure this is outside the Peak Hours. In fact, see if you can shift it to early afternoon as this is when there is the most ambient heat in the air outside even in the Winter.
These three checks will shift your Heat Pump power usage outside the Peak Hours and can be left like that all year round. You may also have a Seasonal Calendar on the timer when you can designate certain months of the year where the Heating is disabled entirely.
You won't save money doing all this (unless we get moved to a Time of Use tariff with hourly pricing) but you will shift your heaviest electrical device outside the National Grid's target hours. You almost certainly won't notice any difference in the warmth of your home or the hot water.
I hope these checks are useful for those of us who have an ASHP system.
