Weather Control or not?

[Agile]

In spite of what you have been told above an 80,000 BTU output boiler is rated at 24 kW.

HOWEVER, that does not mean your boiler is really burning that amount of gas. To check see FAQ or search forum for a gas rating.

You must have a very large house, about 6/7 bedroom detached, for that boiler power. Your heating bills would be at about £2000 p.a. Thats very unusual.

If you have the heating on during the winter does the boiler really burn continuously without cycling?

DP, he says he has already bought the Viessmann. I agree that they have problems. During this summer I called their office and was only answered on the 13th call, others either engaged or timed out on ringing tone. Their staff seem very short term without any real committment to the company. Such a pity when their product is technically very good.

Tony

 

[D_Hailsham]

In spite of what you have been told above an 80,000 BTU output boiler is rated at 24 kW.

I was thinking that my 15 KW boiler was 80,000. It's not, it's 50,000

 

[ditto]

Thanks again - I cannot prove the old boiler did not cycle all I can say is that with the old bellows type room stat when set above 20 deg C on really cold days every time I checked it the stat was asking for heat and I had to turn it below 20 deg C to hear/feel the click as it stopped asking for heat. So I made an assumption that the boiler was running flat out all the time.

I've noticed that the digital stat with a display shows when it is asking for heat and I notice it seems to cycle over 20 deg C. Does the house seem warmer on cold days? I believe so but I'm thinking the 0.5 Deg C switching range calls for heat before the temperature drops too much making it easier for the boiler to top up the temperature?

Maybe its just a feeling, certainly not scientific.

So I'm getting the impression apart from picking a decent boiler (I have to jump and pick one - always pro's and con's), fitting TRV's and good room stat (I'll look into profiling - normally I just turn it up and down) that there is not much more I can do to improve my heating carbon footprint in terms of heat generation. Maybe weather control will help - at least its an option it seems.

 

[sooey]

Maybe weather control will help - at least its an option it seems.

Well, just make sure to control it so that the sun is always shining. That should keep your heating costs down.

 

[Agile]

Boilers cycle on/off when they reach the flow temperature set on their boiler stat.

Thats designed to be a maximum of 80° for standard and 70° condensing.

Is your heating bill really £2000 p.a. ?

The best way to save 30% of your heating bill is to wear a thick pullover and to only heat the rooms you are occupying.

Tony

 

[D_Hailsham]

Boilers cycle on/off when they reach the flow temperature set on their boiler stat.

I thought that the idea of a modulating boilers was to reduce the number of times the boiler switch on/off by adjusting the boiler output to match the heat lost from the house. Something like turning the gas up full on a hob to boil a pan of water then turning it down so the water just simmers. The boiler thermostat effectively acts as an upper limit stat.

 

[BigBurner]

Weather compensation reduces cycling.

 

[Agile]

Boilers cycle on/off when they reach the flow temperature set on their boiler stat.

I thought that the idea of a modulating boilers was to reduce the number of times the boiler switch on/off by adjusting the boiler output to match the heat lost from the house. Something like turning the gas up full on a hob to boil a pan of water then turning it down so the water just simmers. The boiler thermostat effectively acts as an upper limit stat.

Thats quite true!

However, I was referring to the existing 20 y.o. Myson boiler he is currently using which is not modulating.

The main advantage of weather compensation is that it reduces the flow temperature to the minimum which will achieve the required indoor temperature.

This means that the boiler will be more often in condensing mode thus improving efficiency. Its usually expected that the savings will be about 6-14% which is becoming more relevant as gas prices soar.

Tony

 

[D_Hailsham]

However, I was referring to the existing 20 y.o. Myson boiler he is currently using which is not modulating.

Thought you were generalizing; didn't realise you were talking specifics.

I have been putting off the day when I replace my Myson as it has nothing wrong but, the way gas prices are rising, a new one will pay for itself in a year!!

Apart from weather compensation, an intelligent programmer, which adjusts the CH start up time in the morning, would seem essential.

What I don't know is how weather compensation will react with my Honeywell CM927 programmer which has PI control.

 

[ditto]

Thanks for the replies - just back off holiday.

My total gas & electric bill is £1200, House was 4 bed detached, but built extension over double garage/utility (27' x 20') now 7 bed. As I mentioned - trv's all rooms except stat room. Mostly live in kitchen/diner area and all bedroom stats set at 1 or 2 - except when kid turn them up in their rooms.

I will buy weather control option - but why do I need a room stat if I have this - I thought I just picked (trial and error) the heat loss curve and set the weather control accordingly and then it does what ever it does and not use room stat?

Another question - will the boiler regulate burner if I only use a room stat or will it work like my old myson - full on until room stat reaches temperature?

Kind Regards

 

[simond]

Agile wrote

If you have bought a Vitodens 100 they can have an external weather compensation added and you need part number 7818116.

That can be added to any combi or system boiler in that range made since 2005.

Are you sure? I thought only the latest 100W series with the revised PCB could take weather comp.

The 200 series always could, 200 or 200W.

 

[BigBurner]

I will buy weather control option - but why do I need a room stat if I have this - I thought I just picked (trial and error) the heat loss curve and set the weather control accordingly and then it does what ever it does and not use room stat?

Another question - will the boiler regulate burner if I only use a room stat or will it work like my old myson - full on until room stat reaches temperature?

Kind Regards

Many have a room temp sensor/programmer. The main control is the outside temp sensor and it is trimmed off to what the room temp is. It modulates the burner to what the both sensors dictate.

Well worth getting. The problem is that "plumbers" don't understand heating control and the befits it brings.

 

[ditto]

Checked with Viessmann UK. Got a quick reply and Agile is right.

Viessmann quote

"If your Vitodens 100 Boiler has a body number beginning with 7248, you can fit an outside sensor, part no 7818116, which will give you single, fixed curve weather compensation.

The new Brussels boiler, launching in September, also needs the outside sensor, but will have a choice of 3 curves. "


Is an alternative to wc the product here

http://www.warmworld.co.uk/021.html