Optimising hot water schedule

[Glitch]

Started a new thread to avoid hijacking the meter reading one.

After many years of resisting, waiting for compatibility between suppliers, I finally had smart meters installed.

Set up with half hourly readings and downloadable data I could spend hours analysing gas and electricity usage. Occasionally I have a look.
I'm trying to optimise the hot water heating/storage. 3 bursts a day, or just one? I'm thinking it shouldn't really make much difference.

@johna.clements replied:

When the hot water is cooling down it is heating the house. If you are out do you need hot water and heating to the house. I would heat the water when you need a lot of hot water. You could also time your use of the hot water so that you benefit from the waste heat.

The boiler is fairly new and we did get a new, well insulated hot water tank at the same time. Relatively short pipe runs to the bathroom,
Long ones to kitchen, utility room and cloakroom which must lose heat. Exposed hot water pipework is not insulated.
Both retired so usually someone in during the day.

Currently it's hard to predict our use on a day by day basis. Me and the missus tend to alternate daily routines around dog walking but maybe we need to get into more of a fixed routine.
Start showering at the same time perhaps

Avoiding use of the central heating at the moment and will use woodburner to heat downstairs.

I have spotted a strange anomaly in my gas usage. Nothing in the heating or hot water schedule to account for the use after midnight and before 08:00.
Unless that is, the temp drops to under 10.5c which is highly unlikely. Even in these chillier mornings the hall stat is above the 16.5c I had set during the summer.


I've just removed the 18:00 - 18:30 schedule. but the use around 02:30 is a mystery

 

[Pedronicus]

I certainly wouldn't have a program that allows the system to fire up overnight. For morning hot water use set the HW side to come on 1/2 an hour before the heating for a period of 2 hours And then able to run from, say, 1530 to 2100.

You don't say what controls you have but if app based they can be too clever for their own good. Also don't know what system you have installed but it looks like there is a top-up taking place overnight. More info needed for detailed advice.

 

[Glitch]

I use Nest.
I can see in the App usage history that there is no call for heat from the thermostat.



I think the idea of heating the hot water before the room heating is a good one. Better to heat one circuit at a time rather than two.
Interesting suggestion about 15:30 - 21:00 I guess it shouldn't need much to keep the heat topped up.

Only other gas appliances are the burners on the cooker.

The mystery use could only be hot water.
I'm ruling out leaks.
I could ask our heating engineer if he has any ideas.

 

[johna.clements]

It is strange that the hot water is heating at 200 in the morning. Maybe Rumpelstiltskin is running a laundry at night.

 

[Glitch]

Schedules are very simple

 

[Spectric]

Everything will be a balance between the heat losses from the system and periods of usage. There is no point in heating the hot water too late in the day if the next period of high usage is the next day. I have an OSO cylinder that is well insulated and an unvented system using a Worcester boiler, the hot water comes on around 7:00 Am for thirty minutes and then around 4:00 Pm for thirty minutes and that is that, if we need extra then there is the overide on the controller.

Exposed hot water pipework is not insulated.

That is not good, the hot water supply pipework should be well insulated to prevent heat losses, also to protect from freezing.

The overall efficiency of a system is not down to individual components but the complete system design so to get the best efficiency, it cannot be achieved by just replacing the odd component. The pump / circulator is another area where savings can be made, ensure the pump is fitted into the return pipework to the boiler which reduces it's running temperature and use a smart Grunfoss pump like

https://product-selection.grundfos....72?pumpsystemid=1667973267&tab=variant-curves
This pump uses less energy because it matches it's flow to the current demand, but you cannot use pressure operated bypass valves in the system.

 

[Glitch]

Only had these overnight anomalies 5 nights in the past week and nothing before then.

I have a vented system with an insulated copper cylinder. I will insulate the pipes.

The pump put in when the boiler was replaced was not up to the job and got upgraded. Still not as good as the old one.

 

[Pedronicus]

If you have the Gen 3 Nest then it can also control the hot water. If so then check that the HW is not set for 24hr operation. If just a standard timeswitch to control the HW then check to see if it is not set to Constant or 24 Hr. If so then set it to a timed programme to suit your needs.

 

[Glitch]

If you have the Gen 3 Nest then it can also control the hot water. If so then check that the HW is not set for 24hr operation. If just a standard timeswitch to control the HW then check to see if it is not set to Constant or 24 Hr. If so then set it to a timed programme to suit your needs.

HW only comes on twice a day (from today) previously three times. Definitely not set to 24hrs.

 

[selectortone]

Many here probably know this, but it's worth mentioning: Turning down the temperature control on the boiler and the temperature sensor on the hot water tank has made a significant improvement to my gas consumption. For years - since I had a new boiler installed - it was scalding hot and having a shower or washing up required mixing in lots of cold water. I had a light bulb moment when I was warning my daughter about my granddaughter using the shower.

 

[johna.clements]

Many here probably know this, but it's worth mentioning: Turning down the temperature control on the boiler and the temperature sensor on the hot water tank has made a significant improvement to my gas consumption. For years - since I had a new boiler installed - it was scalding hot and having a shower or washing up required mixing in lots of cold water. I had a light bulb moment when I was warning my daughter about my granddaughter using the shower.

As long as you do not turn it down too low so legionella bacteria grow.

 

[Glitch]

60-65c is the recommended temperature

 

[Mal-110]

We have a similar system to yours. On checking gas usage on the suppliers app we found 13p or 14p’s worth of gas used every other morning whilst we were away. The hot water and central heating were all off. Contacted the supplier and it does not happen now. No explanation was given but we presume they have re-calibrated the new smart meter.
It may well be a good idea to turn everything off for a day to check that the meter is reading properly.

 

[Pedronicus]

Yet another reason not to have a Smart Meter!

 

[Glitch]

We have a similar system to yours. On checking gas usage on the suppliers app we found 13p or 14p’s worth of gas used every other morning whilst we were away. The hot water and central heating were all off. Contacted the supplier and it does not happen now. No explanation was given but we presume they have re-calibrated the new smart meter.
It may well be a good idea to turn everything off for a day to check that the meter is reading properly.

I'm going to change the schedule again on the back of advice and I'll keep an eye on it.
I'm with London Power (Octopus Energy). I'll take it up with them if there is further unexplained consumption.

 

[Glitch]

Yet another reason not to have a Smart Meter!

At least it is telling me there's a potential issue!

Unless you stay up all night doing meter readings how would you know you have unexplained consumption with your dumb meter?

 

[Spectric]

No explanation was given but we presume they have re-calibrated the new smart meter.

A smart meter gives the supplier complete control over your energy cost, what it determines as usage can also be changed but a non smart meter is a simple device that has been in use for decades with a proven track record of reliability and honesty.

 

[NormanB]

I certainly wouldn't have a program that allows the system to fire up overnight. For morning hot water use set the HW side to come on 1/2 an hour before the heating for a period of 2 hours And then able to run from, say, 1530 to 2100.

You don't say what controls you have but if app based they can be too clever for their own good. Also don't know what system you have installed but it looks like there is a top-up taking place overnight. More info needed for detailed advice.

First is your boiler in the garage?

Second in broad terms (all other things being equal) the hotter you drive your water temperature up the greater the rate of heat loss. You need to match your DHW schedule to your useage. We have a 210 litre DHW cylinder and raise the temperature every other day to 50 deg C, once a week to 60 (risk reduction legionella).

 

[Glitch]

A smart meter gives the supplier complete control over your energy cost, what it determines as usage can also be changed but a non smart meter is a simple device that has been in use for decades with a proven track record of reliability and honesty.

Sounds like conspiracy theory stuff to me. Presumably the suppliers are acting as a cartel and all in on it?

Perhaps you can give some examples of suppliers manipulating usage.

 

[Glitch]

First is your boiler in the garage?

Second in broad terms (all other things being equal) the hotter you drive your water temperature up the greater the rate of heat loss. You need to match your DHW schedule to your useage. We have a 210 litre DHW cylinder and raise the temperature every other day to 50 deg C, once a week to 60 (risk reduction legionella).

Sounds like a faff to me.

I've been swayed towards heating the HW just before it's needed, e.g., daily showers. If heated to 60c it has a lot less time to lose the heat and as it gets used the temp comes down anyway.

If I don't have a regular shower schedule then a 30 min boost before we need it is probably even more efficient. remaining water should be hot enough for other uses the rest of the time.