Gas boiler thermostat

gaiscioch

Hi,

We've just moved into this place and our hot water is roasting, although I cannot describe the radiators similarly. We have gas central heating which we've never had before and I notice that the previous person had it up at Max (see picture 4). As the weather hasn't been really cold, is there any particular reason why somebody would leave this gas boiler at max? (this post: "The higher this is set, the quicker and more effectively the system will heat your home" prompted me to ask this rather than just turning it down) What sort of temperature should it be at?

Picture 1

Picture 2

Picture 3

Picture 4

antoinolachtnai

The real question is why your radiators are not as hot as your hot water. The answer is probably that there is a valve somewhere that is closed, or it may be that there is some fault. I would really ask the landlord if it is a rental.

In terms of the ideal temperature to set a boiler at, it is actually quite a complex question. I think the 'safe' answer is for it to be hot enough to kill any bacteria in the hot water tank to minimise the risk of Legionnaire's Disease.

The 'environmentally friendly' answer with a modern condensing boiler (I am not sure that that boiler fits the category) is to run it as cool as possible while still providing adequate heat. This maximises efficiency.

I am sure there will be other views on this.

gaiscioch

Thanks.

Since I put the thermostat down around 10 hours ago, the stat light has remained at yellow rather than its previous green when it was at Max. The water temperature is now fine, but I'm wondering is that light a warning of some sort now.

nmacc

antoinolachtnai wrote: »

The real question is why your radiators are not as hot as your hot water. The answer is probably that there is a valve somewhere that is closed, or it may be that there is some fault. I would really ask the landlord if it is a rental.

In terms of the ideal temperature to set a boiler at, it is actually quite a complex question. I think the 'safe' answer is for it to be hot enough to kill any bacteria in the hot water tank to minimise the risk of Legionnaire's Disease.

The 'environmentally friendly' answer with a modern condensing boiler (I am not sure that that boiler fits the category) is to run it as cool as possible while still providing adequate heat. This maximises efficiency.

I am sure there will be other views on this.

Agreed.

The most likely cause of the temperature difference is the balancing valve on your hot water cylinder being open too far. That way the hot water from the boiler dashes around the cylinder coil getting the water good and hot, but being lazy, it doesn't spend much time wandering around the radiators. The cure is to find the balancing valve, which will be on the 3/4" pipe going into the side of the hot water cylinder, 2/3 or 3/4 of the way up. You need to close this valve down a bit to force the water around the radiators. Trial and error is your best bet.

For a condensing boiler to operate at its best the return water temperature should be 55C or less, meaning that the flow temperature should be 65C or less. At those temperatures Legionella won't be a problem. Either way 'tis not relevant as it's not a condensing boiler and since the cylinder is copper, Legionella doesn't arise either.

I can never remember what the colour of the LED on that model means. I don't think yellow is a problem, but I'm sure someone will quickly put me right if it is.

Wearb

nmacc wrote: »

Agreed.

The most likely cause of the temperature difference is the balancing valve on your hot water cylinder being open too far. That way the hot water from the boiler dashes around the cylinder coil getting the water good and hot, but being lazy, it doesn't spend much time wandering around the radiators. The cure is to find the balancing valve, which will be on the 3/4" pipe going into the side of the hot water cylinder, 2/3 or 3/4 of the way up. You need to close this valve down a bit to force the water around the radiators. Trial and error is your best bet.

For a condensing boiler to operate at its best the return water temperature should be 55C or less, meaning that the flow temperature should be 65C or less. At those temperatures Legionella won't be a problem. Either way 'tis not relevant as it's not a condensing boiler and since the cylinder is copper, Legionella doesn't arise either.

I can never remember what the colour of the LED on that model means. I don't think yellow is a problem, but I'm sure someone will quickly put me right if it is.

I never before heard that having a copper cylinder prevents legionella. Am I reading your post incorrectly?

nmacc

Wearb wrote: »

I never before heard that having a copper cylinder prevents legionella. Am I reading your post incorrectly?

Nope, you read correctly. Copper is toxic to Legionella.

Wearb

nmacc wrote: »

Nope, you read correctly. Copper is toxic to Legionella.

Thanks. I had thought that it just retarded it's growth rather than preventing it outright.

Dtp1979

nmacc wrote: »

Nope, you read correctly. Copper is toxic to Legionella.

Really?? Any facts to prove this? Your saying it's ok to store water at 45 degrees in a copper cylinder?

Egass13

Dtp1979 wrote: »

Really?? Any facts to prove this? Your saying it's ok to store water at 45 degrees in a copper cylinder?

I wouldn't of thought so either , first I've heard of it . Be interested to see the proof

nmacc

Dtp1979 wrote: »

Really?? Any facts to prove this?

Any facts? Yes. I suggest you look them up. Alternately you could do as I did, and pay to take the course.

Dtp1979 wrote: »

Your saying it's ok to store water at 45 degrees in a copper cylinder?

If it bothers you, then don't do it.

Egass13

nmacc wrote: »

Any facts? Yes. I suggest you look them up. Alternately you could do as I did, and pay to take the course.



If it bothers you, then don't do it.

That is a very helpful answer nmacc. Then again it is standard boards procedure , ask for links so that it can prove the point being made , be met with arrogance and smart arsedness . Nobody said your wrong. Just that it was the first we had heard of it and would like to see some documentation of your claim. So if that's at all possible , I'd still be interested to learn more about it .
Thanks.

Dtp1979

Me thinks we're not gonna see links...
And what course teaches this??

antoinolachtnai

The 'UK Copper Board', who one would presume are an interested party in the promotion of the merits of copper plumbing, do not make this claim in their literature. I note they recommend having the system at 55 degrees Celsius, amongst other recommendations, to minimise the risk.

http://www.ukcopperboard.co.uk/literature/pdfs/Installation-Tips/Legionella-and-copper-plumbing.pdf

The Copper Board refer to guidance which is a bit old. The current UK guidance that seems most relevant to me is http://www.hse.gov.uk/Pubns/priced/l8.pdf

This guidance does not contain the word 'copper' as far as I can tell.

If there are training materials recommending the use of copper as an alternative to normal legionella precautions, it would be as well to refer them to the HSA.

The best practice way to plumb a gas heating system, as far as I can see, is to have different temperatures at the boiler for the hot water and the central heating. Anything else might be easier to plumb, or might have simpler controls, or might be more 'intuitive' for the householder, but in terms of safety and efficiency, it is going to be second-best.