BAXI Gas Central Heating Boiler query

shutter · ‎06-11-2007

@VileReynard wrote:

Assuming your boiler is an appropriate capacity, maxing out the two controls means your hot water ought to be scalding hot and you will have super hot radiators (after you have bled each one).

This causes high gas bills.

Interesting concept..... "causes high gas bills"....

Surely,... if you want your "heating" to work, you must make the radiators hot enough to warm up the surrounding air, and "convect" that warmed air, around the space you are trying to heat...

once the air temperature has been raised to the required "ambient temperature" ( set on the controls) the gas is then shut down, and the radiators continue to convect the warmed air around them...

if you have the "hot water in the system" just warm, then that will use more gas to heat the air around the raiators and for a longer time, to reach the "ambient" temperature you have set...

conversely... if the hot water in the system is near boiling, then the air will be heated quicker, and after the ambient temperature is reached, and the gas is shut down, it will take longer for the radiators to cool down, thus providing more "latent" heating time than a "warm" system that you are suggesting .

By the way.... you sidestepped answering my question in post number 12

@VileReynard dunno ! ... that`s the way he left it... seems ok to me... !

what is "usual" if i is "unusual" ?

VileReynard · ‎01-09-2007

I didn't sidestep anything - @Mook answered your query about what is "normal".

It seems obvious that if you run that boiler at a higher than necessary temperature it is going to be a less efficient system.

I suggest you check with the engineer when your boiler gets its annual service.

"In The Beginning Was The Word, And The Word Was Aardvark."

Baldrick1 · ‎30-06-2016

@shutter

If you want to get the maximum efficiency out of your condensing boiler then you need to set the temperature so that the return flow is less than the dew point, that is, about 55 degrees C. The feed temperature has to be higher than this for the condensing cycle to work but unless the return is sufficiently low the condensing cycle fails and the boiler efficiency drops.

Moderator and Customer
If this helped - select the Thumb
If it fixed it, help others - select 'This Fixed My Problem'

shutter · ‎06-11-2007

@Baldrick1 Thanks for the input. which is totally confusing me. ! ! ...

As I understand it.... the "dewpoint" can change hourly,...( as confirmed by listening to VOLMET channel )

Strat · ‎14-04-2007

I have come across lots of people who, in Winter, turn the room stat up full when returning home.

They do this in the belief that the house will warm up quicker.

I used to have a book of formulae pertaining to installing and setting up central heating.

Things like flow rates and outflow temperature v return temperature and balancing radiators.

Thankfully I don't have it any more.

Windows 10 Firefox 109.0 (64-bit)
To argue with someone who has renounced the use of reason is like administering medicine to the dead - Thomas Paine

Baldrick1 · ‎30-06-2016

@shutter

I agree that this is all very confusing. I have no idea what volmet is.

The thing to remember is that whilst dew point with respect to depositing moisture on your windows depends on the atmospheric relative humidity and temperature, so is variable, what we are talking about here is the humidity of burning gas. Google et al tell me that this has a dew point of about 55 degrees C.

Moderator and Customer
If this helped - select the Thumb
If it fixed it, help others - select 'This Fixed My Problem'

shutter · ‎06-11-2007

@Baldrick1 VOLMET is a service provided to air traffic, in particular airline pilots, if a pilot has problems, he will need to know the weather information for any diversion . a pre recorded message containing "local" airport information is broadcast on a set of frequencies... the information gives the location...i.e. Glasgow... and for that airport it would include reports such as..... Visibility... cloud heights and types.... wind speed,, wind direction. atmospheric pressure in mbs. and the recent weather, plus a forecast in brief terms, temperature, and the "dewpoint" when applicable...

It is a worldwide setup... and all airports are covered, in specific areas of transmission. eg. u.k.. europe. med...etc.

Baldrick1 · ‎30-06-2016

@shutter

Ah, so dew point in this context is all about atmospheric conditons and the possibility of fog formation, nothing to do with gas central heating boilers. As these boilers burn a mixture of air and gas then I assume that the humidity of the air used will have some sort of affect but I suspect that this is lost in the noise compared with the dew point of the burning gas.

Moderator and Customer
If this helped - select the Thumb
If it fixed it, help others - select 'This Fixed My Problem'

VileReynard · ‎01-09-2007

The burnt gas will be a mixture of air, CO2 and water vapour - at atmospheric pressure.

It will be hot.

Because you have a closed system, the return feed is the only water available to extract the waste heat from the flue gases.

If it is below the dew point (55C) it will succeed in condensing the waste water vapour.

In doing so the return feed becomes warmed, which increases the boiler efficiency.