Boiler constantly on. What am I doing wrong ?

[Mark Mitchell]

Hi DIYNOT people,

We have inherited a very confusing (for me anyway) central heating system.

There is a boiler in the garage and a water tank on the first floor next to the baths/showers.

It is a Honeywell system with a portable wireless thermostat.

Even when the heating is turned off, the boiler is constantly on and the hot water tank is full of hot water.

There are only three of us in the household, so I'd expect the boiler to be able to deliver all the hot water we need.

I have attached photos of the system. Can anyone advise me of the most energy efficient settings ? I'm sure we are wasting a fortune by having the boiler on constantly and the hot water tank seemingly full all the time, especially at this time of the year.

All advice will be gratefully received.

Cheers

Mark

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[muggles]

Are you saying that the boiler is on even when both timers are set to off?

Your cylinder thermostat is set a little high - turn it down to 55°C

 

[mrStat]

Get a heating engineer to pop out and take a look - If nothing else, if you've moved into a new house, a gas safety check is a good investment and a boiler service will at least give you a rough idea of how much life is left in the old girl... At the same time get them to run you through the system setup (Most will happily run through a system setup).

You have a Y-Plan system by the looks of it, the clock in the airing cupboard should be responsible for the hot water - Set this to be on for around 45 minutes before you start consuming lots of hot water (Shower time) and then let it run on for 15 minutes after the shower time window. The slider needs to be set to "Run Programme" and then switch it to "Auto" - At the moment you have it on all day long, "Once" = on at the earliest time point, off at the latest set time point within the programme.

The CM927 is a programmable heating thermostat, download the manual for it. In short, flick it to "man" and you can use it as an up/down thermostat, programme it using the manual.

And yes, as per Muggles, the position of the cylinder stat on the tank is not ideal, having it set that high is a bit ambitious, the boiler will probably never be able to raise the temperature that high at that point in the tank - Plus you'd have volcanic hot water. On the boiler you have a "Radiator" temperature set, this should be 70 degrees roughly depending on the system type and size. If the cylinder stat is set to high, the boiler will never be able to raise the temperature to the set level and will appear as though it is always running.

 

[ianmcd]

Are you saying that the boiler is on even when both timers are set to off?

Your cylinder thermostat is set a little high - turn it down to 55°C

To prevent the formation of Legionella the water in the cylinder should be stored at 60 degrees C or higher

 

[muggles]

To prevent the formation of Legionella the water in the cylinder should be stored at 60 degrees C or higher

Correct, and setting a thermostat a third of the way up the cylinder to 55 will ensure a temperature of over 60 at the top, because stratification

 

[MeldrewsMate]

... the clock in the airing cupboard should be responsible for the hot water - Set this to be on for around 45 minutes before you start consuming lots of hot water (Shower time) and then let it run on for 15 minutes after the shower time window.

I agree with most of MrStat's post, but disagree that you should time it to reheat for 15 minutes beyond showering time. The most economical way to run hot water is to heat it up just before you need it, and no longer, ie have a tankful of cool water between uses so less heat is lost to its surroundings.
Of course only you can decide what those periods are.
I think MrStat may have confused @muggles' comment about the tank 'stat temperature being set too high (70C) with its position on the cylinder.

MM

 

[mrStat]

I agree with most of MrStat's post, but disagree that you should time it to reheat for 15 minutes beyond showering time. The most economical way to run hot water is to heat it up just before you need it, and no longer, ie have a tankful of cool water between uses so less heat is lost to its surroundings.
Of course only you can decide what those periods are.
I think MrStat may have confused @muggles' comment about the tank 'stat temperature being set too high (70C) with its position on the cylinder.

MM

That's fair enough... To be honest, I will always balance convenience over the cost... I suppose if you are looking for 100% economy, then yes, switch off a couple of minutes before the showering ends, just make sure you don't need to run too many sinks of hot water off during the day and that you may need to boost it if several people are showering and the first person is running behind schedule; the joys of a traditional system - Although I personally prefer them still over combi's.

As for the stat position. Just looks a bit low to me; plus the temp is probably too high... Was always told 1/3 from bottom; looks more like 1/5 - But who knows? Cylinder stat must always be set lower than the boiler thermostat... Forgot to mention a key point - If you have the model with the two temp dials, 1 for CH and 1 for HW - Ignore the HW one, it does diddly squat on your type of system.

 

[Mark Mitchell]

Thanks to everyone for your replies.

I have moved the thermostat on the cylinder to 55 degrees and have set the programmable unit in the airing cupboard to come on twice. For a period in the morning and the evening.

The boiler is now longer on all the time and I reckon I will be saving quite a bit of money going forward, by not heating a hot water tank all day. I have also booked in a heating engineer to carry out a gas safety check and a boiler service.

Really appreciate everyone's time and energy in replying to my post. You are superb !!!!!!