Most efficient boiler settings

blagoslovljena

I have a Worcester Greenstar 30Si boiler circa 2008 that has recently had most of its innards replaced on my BG homecare contract due to a crack in the heat exchanger. I’m assuming it’s running more efficiently as a result anyway, but I heard the guy in charge of Octopus Energy on the radio the other day saying that people could save 20-30% on their heating costs just by adjusting the boiler settings.

Does anyone know what settings are most efficient for my boiler? Because it’s ancient by boiler standards it doesn’t have any digital controls, literally a dial for heating and another for hot water. Heating dial runs from 1-6, then ‘max’, and hot water the same but with a ‘min’ setting before the 1 and 5 is replaced with ‘e’. I’ve had a look around online to no avail, and the manual’s no help.

TimSynths

"Off".                           .

blagoslovljena

TimSynths said:

"Off".                           .

🤣 Unfortunately not an option in these temperatures with four kids at home all day!

Bendy_House

Hi Blag.

Lol - good answer by Tim

Although 'old', your boiler IS a condensing type, yes? In which case the most efficient setting is 'as cool as possible'.

In essence, the cooler you can set your CH control, provided it still keeps your house warm, the slightly more efficient your boiler will be running. This is because the cooler the 'return' temp of water from your radiators, the more heat that 'cool' water can extract from your boiler's flue. Heat that would otherwise heat the seagulls.

I really dislike these sorts of programs, tho', as what is usually said is a bit misleading. It'll almost always be the most extreme example. 20 to 30% savings?! You are having a giraffe.

Questions to ask yourself - is your boiler CH control set as low as it can be, whilst still allowing your house to heat up as you require? Is your CH timed to come on only when you need it to? And only at the temps you actually require? In short, do you have a Programmable Thermostat fitted?

ashe

Suppose youd only get those savings if everything was set to max. I tried turning mine down a lot and the rads got hot a LOT slower and took a lot longer to heat the house. Turning max hot water temp down was a result tho as that was always scalding. 

Turn boiler down a degree at a time until it seems like you've gone too far. 

Then, if you have TRV's, set each room to the proper setting - its the room temp not the rad temp. 

blagoslovljena

Thanks for your input guys!

I actually homeschool so we’re in the house pretty much all the time, plus our house has long-standing condensation issues (a problem with many houses on my estate - we live next to a brook and the air is always humid as a result), not helped by having 6 people living in a small 3 bed, 5 of whom are at home all day. 

To prevent mould build-up we have to run a dehumidifier and keep the heating on 24/7 in winter, which is obviously less than ideal. So in terms of the house taking a long time to heat up, it never really gets cold. 

I guess turning down the boiler heat setting might be the way to go then, as it’s not an option to switch it off, and also turning down the hot water unless I’m having a bath?

blagoslovljena

And is it better to have the TRVs on max but the boiler CH set lower rather than the other way round then? I’ve generally gone for high-ish on the boiler and keeping the TRVs set lower… 🤔

Ectophile

The TRVs should be set according to the temperature you want in that room.  So if you want to keep the room warm, turn it up.  For rooms you aren't using turn it down.  The TRV turns the flow to the radiator on and off to achieve the setting you've dialled in.  That's the sace whatever temperature you set the heating to at the boiler.

BUFF

It's a combi, right?
what controls do you have (programmer, roomstat)? I gather that you have TRVs.

You can have both the boiler set lower & the TRVs.

If you have the TRVs on max they will always be open/calling for heat as it's unlikely that your rooms will ever reach the temp (max is  usually ~28C+). Set them to what you want the individual room temp. to be* - try the 3 setting to start with in rooms in use & adjust from there if you feel too cold/hot. Rooms not in use can have a lower setting.

*there is an exception if you have a TRV in the same room as a roomstat. Then you would open the TRV to max. & let the roomstat control.

Bendy_House

blagoslovljena said:

1) And is it better to have the TRVs on max but the boiler CH set lower rather than the other way round then? I’ve generally gone for high-ish on the boiler and keeping the TRVs set lower… 🤔

2) "I guess turning down the boiler heat setting might be the way to go then, as it’s not an option to switch it off, and also turning down the hot water unless I’m having a bath?"

1) As said above, the TRVs for each room should be set to provide the level of heating required for that room. That's roughly '3' for 'living' areas (~20oC), around '2' for bedrooms, etc. And when a room does not need heating - bedrooms during the day, for example - then close these TRVs right down. If you get condensation in the bedrooms, close their doors and crack open their windows to 'vent' setting during the day, and even overnight if you can. Heating off as you do so.

With the TRVs set at their respective positions for each room, you then have the boiler's CH temp output set as low as possible that still does the job - ie gets the house up to temp in the morning, and maintains it during the day as required, ideally with the boiler shutting off at periods when it's done its job. This will vary from day to day according to the outside temp.

Yes, there is the risk of turning the boiler CH temp down set so low that the rads never get hot enough to actually properly heat the house, so that will mean the boiler will be running constantly and your house will not be heated fully. So, if you have a temp gauge on it, try it at, say, 70oC CH flow temp to start with, and see how that goes - it should heat your house successfully. It should hopefully give you a return water temp of below 60oC, and that should be getting in to condensing territory - a nice visible plume from your flue. If that seems to work fine for heating your house, then by all means try dropping it a few degrees lower - say to ~65oC flow temp - and that should be even more efficient. However, if you now find that your boiler hasn't managed to get your house warm quickly enough in the morning, or if the boiler just seems to be running and running in order to maintain your house temp, you may decide to tweak it up a bit more.

2) If your boiler is a combi type, heating DHW on demand, then just set and leave the DHW output control to ~60oC, and that will be fine. If your boiler heats a stored hot cylinder of water, then you are best to set heating times for just before the water is needed - that could be, say, 30 minutes heating in the morning before folk get up, and then another 30-45 minutes late afternoon/early evening to provide DHW for washing up and showers. Do not have the cylinder heated at times when it is not required; just work out how much heating it needed to get the right amount of water to the right temp for each occasion. 

blagoslovljena

That’s really helpful guys, thank you. 😊

It is a combi (no hot water tank) with no remote thermostat anywhere and just the TRVs to control the temperature in the rooms. There’s two dials on the boiler with literally just a 1-6 and ‘max’ on each, to control the CH and HW. 

There’s a programmable analogue-style clock - all very old school! But we don’t use the timer function for it as the CH is literally on all the time at this time of year and we’re using all the rooms in the house (small house, lots of people). When it warms up a bit weather-wise I manually turn the CH on in the morning and off when I go to bed, as if I set the timer the noise of the radiators heating up before we get up wakes my kids. 🙄

TRVs are usually on 2 in each room, unless the temperature drops, when I might turn it up a bit in the lounge and bedrooms. I have baby monitors in two of the bedrooms and they usually show room temp as 21-22 degrees, but I can’t really have it lower as I have young kids at home all day.

I tried turning the CH dial on the boiler from 4 to 3 last night, and the HW dial from the ‘e’ setting (whatever that means - it’s where the 5 should be!) to 4, and so far I haven’t noticed any difference, so I think I’ll see how things go today and possibly turn them down again. There’s no digital display or anything to indicate actual temperature on the boiler, so I’m largely just winging it! 🤣