Immersion(s) vs. Programmer for hot water

[dpm_dpmartin]

Morning gents,

After a recent boiler scare (just on Friday) I had a company around to do some fixing and a service of my unvented system. Everything is back up and running... happy days.

I do - however - have a few questions that I hoped the members here might help me with to obtain a better understanding of the system in my house.

The system has been in since, I think, 2011, but I've only owned the house since mid-2014 and it has "just worked" until Friday when it... well, when it didn't.

The company that rescued me fixed the issue with the top tank expansion vessel being full of water - which is great. They also serviced the system and it all passed with the tests they did. However, they also took the opportunity to improve my system and this has meant a few changes were introduced at the same time.

Up until Friday, my programmer in the boiler cupboard had Water and Heating both set to OFF.

Nest controls my heating. Water seemed to be done by 2 immersion heaters that were in the big (300 litres) tank - one at the bottom of the tank, one half-way up. These were switched on constantly and the guys said this probably wasn't a good idea and recommended a change.

They suggested I set up a programme on my programmer to heat water a couple of times a day but we discussed whether having the programmer switched to Hot Water CONTINUOUS, but both immersion heaters off, was effectively the same. We agreed it was.

So that's how we left it - at my request.

Both immersion heaters are switched off. The programmer is set to Hot Water CONTINUOUS.

Now, this seems to mean the boiler is kicking-in a lot more. And I can hear it doing its thing.

No surprises there.

But I am contemplating going back to how it was. It seemed a lot less intrusive that way (my home office is quite close to the boiler cupboard - on the same floor - and I can hear it droning away most of the day).

Am I bonkers to want to go back to how it was?

Please bear in mind I'm just a layman, but I want to understand why I now have something that is different and not - noticeably - any better for me... but maybe that benefit will be in my pocket in the future (although my electricity bills were never that bad - in my eyes).

As always, I appreciate anyone who takes the time to provide me with some insight here.

One positive - I will get the system serviced every year now. I'm already booked-in for 2017.

 

[Echo the husky]

What fuel does your boiler use? It will be far cheaper to heat the water with most boilers than with the electric elements. Why not set up the hot water times rather than leaving it on continuous? That way the boiler wont be disturbing you by firing every time the temperature drops a bit. Try a few hours early in the morning and a few hours late afternoon as a starting point, and then adjust the times as needed bearing in mind 300L is fairly big. The times should be long enough that the cylinder is able to reach the temperature set on the cylinder thermostat. If the timer is always switching off too soon and the water never reaches full temperature, there is a risk of legionella growth.

 

[dpm_dpmartin]

It's a gas boiler... normal gas.

Cheaper is good, of course. I do not dismiss that out-of-hand... it's just that everything was working fine for many months and now something has changed (as part of a repair) and I'm not sure whether I like it... or I want it back as it was (which I can do, obviously, as it's just settings).

I didn't get to choose the size of tank, I'm afraid... 300 is just what it is. It seems like the boiler is firing pretty much all the time now... it's going now (I realise I put it on CONTINUOUS, but obviously that doesn't mean it's continuously on... it does turn off sometimes.

You can tell I'm conflicted.

I don't know why I also think I'm protecting the boiler's longevity by having the immersions doing their thing too. Could be completely wrong.

Thanks for your thoughts, by the way.

 

[muggles]

Heating the water with your immersion heaters will cost you three to four times what it does to heat using the gas. Keep it as it is, but set times up for the hot water so that is only heating when you need it - it'll only take about 30 minutes to heat your cylinder with the boiler, so there's no reason to have it on continuously, just time it to come on when you normally need a large quantity of hot water

 

[dpm_dpmartin]

Thak you. I need to get my head around this and accept the extra noise the boiler is putting out (or ensure that programme is created ASAP).

 

[hazetimesfive]

How much water is being used? modern insulated cylinders dont lose much heat.