Oil boiler questions

Andy From Sligo

Hello its me again

You know as a outside boiler module turns on from cold , at the same time the pump starts circulating the water in the boiler to the rads and then back into the boiler. Is this the most efficient way that boilers work.

Wouldn't it be better to heat up the water in the boiler to 60/65c first and then with a pipe thermostat turn on the pump only and only when the water reaches 60/65c to start circulating? - so its not trying to heat the water as its passing through the circuit whilst its cooling down?

Would the water still expand and vent ok to a certain extent still if the pump wasnt on and it being 22mm pipe and not 28mm gravity?

Just curious , im not going to go re-wiring CH pumps or anything

Robbie.G

Andy From Sligo wrote: »

Hello its me again

You know as a outside boiler module turns on from cold , at the same time the pump starts circulating the water in the boiler to the rads and then back into the boiler. Is this the most efficient way that boilers work.

Wouldn't it be better to heat up the water in the boiler to 60/65c first and then with a pipe thermostat turn on the pump only and only when the water reaches 60/65c to start circulating? - so its not trying to heat the water as its passing through the circuit whilst its cooling down?

Would the water still expand and vent ok to a certain extent still if the pump wasnt on and it being 22mm pipe and not 28mm gravity?

Just curious , im not going to go re-wiring CH pumps or anything

If you turn off a circulating pump and turn on the boiler it will reach temp very quickly as it is a small volume of water a couple of litres
So there is no benefit to time delay the pump it would do nothing to the overall heat or recovery of the heating

Andy From Sligo

My present outside condenser boiler has a RDB2 Burner which I understand is a single stage burner - but the previous ol boiler in our previous house was an old stanley 80 range indoor boiler which had 2 burners (1 for the cooker part and one burner for the central heating rads/immersion tank) - but as far as I know it had a 2 stage burner fitted to it.

Whats more economical? a 2 stage burner or single stage? - or is there nothing between it?

Whats the difference between the 2 - is one better burner than the other.

Can a 2 stage kerosene burner (if its better or more economical) ever be fitted to the grant euroflame outdoor condenser boiler at a later date if I wanted to? (the burner blast tubes do look the same on both single stage and 2 stage burners. )

I tried googling but it just seems to come up with a load of US details about burners (or furnaces as they call them)

jimf

andy I love all your questions and enjoy them to an extent

but would you by any chance dissect the fridge or the washing machine for a change

Andy From Sligo

jimf wrote: »

andy I love all your questions and enjoy them to an extent

but would you by any chance dissect the fridge or the washing machine for a change

not as much fun

JamesM

Andy From Sligo wrote: »

My present outside condenser boiler has a RDB2 Burner which I understand is a single stage burner - but the previous ol boiler in our previous house was an old stanley 80 range indoor boiler which had 2 burners (1 for the cooker part and one burner for the central heating rads/immersion tank) - but as far as I know it had a 2 stage burner fitted to it.

Whats more economical? a 2 stage burner or single stage? - or is there nothing between it?

Whats the difference between the 2 - is one better burner than the other.

Can a 2 stage kerosene burner (if its better or more economical) ever be fitted to the grant euroflame outdoor condenser boiler at a later date if I wanted to? (the burner blast tubes do look the same on both single stage and 2 stage burners. )

I tried googling but it just seems to come up with a load of US details about burners (or furnaces as they call them)

Come on Tom - Answer the man !

TPM

Andy From Sligo wrote: »

Hello its me again

You know as a outside boiler module turns on from cold , at the same time the pump starts circulating the water in the boiler to the rads and then back into the boiler. Is this the most efficient way that boilers work.

Wouldn't it be better to heat up the water in the boiler to 60/65c first and then with a pipe thermostat turn on the pump only and only when the water reaches 60/65c to start circulating? - so its not trying to heat the water as its passing through the circuit whilst its cooling down?

Would the water still expand and vent ok to a certain extent still if the pump wasnt on and it being 22mm pipe and not 28mm gravity?

Just curious , im not going to go re-wiring CH pumps or anything

if you had a stat which only let the pump start above 60c
the boiler would turn on reach 60c
the pump would switch on for a very short time
the cold return water would cool the boiler quickly
the pump would turn off.
the hot water from the boiler most likely would not reach the first rad.


the boiler would reach 60c again
the pump would switch on for a very short time
the cold return water would cool the boiler quickly
the pump would turn off.
the hot water from the first cycle would be pumped further through the system but would have lost some of its heat

these cycles would keep repeating untill the return temp is high enough to stop it possibly resulting in greater heat loss and slower heat up time

TPM

forget 2 stage hold out for the blue flame modulating burners that are on the way

Tom44

JamesM wrote: »

Come on Tom - Answer the man !

www.penddraig.co.uk/online-tests/the-insanity-test

jimf

TPM wrote: »

forget 2 stage hold out for the blue flame modulating burners that are on the way

you do realise he is going to ask you to explain blue flame :mad::mad::mad:

K.Flyer

jimf wrote: »

you do realise he is going to ask you to explain blue flame :mad::mad::mad:

Ah whisht will ya, don't be starting him off! :pac:

Andy From Sligo

When my boiler first starts up in the morning it only heats upstairs rads and immersion tank and fair enough once its cold the burner stays on a long time to heat it up to 60-65c , but once its reached temp in the boiler then even though the rads and immersion is still calling for heat the boiler burner keeps going into an on/off cycling mode then (keeping its heat I suppose) and then starts for a while, stops for a while and then starts again soon (so maybe off for a min then on for a minute then off for a minute) I have heard that this cycling on and off is not good for the boiler as it can shorten its life? What does it shorten is it the electrodes and the high voltage transformer because it has to stop and ingnite more than it should, is that what it is? - any ideas how to stop it cycling on and off like this? Thanks

DGOBS

if you had a stat which only let the pump start above 60c
the boiler would turn on reach 60c
the pump would switch on for a very short time
the cold return water would cool the boiler quickly
the pump would turn off.
the hot water from the boiler most likely would not reach the first rad.


the boiler would reach 60c again
the pump would switch on for a very short time
the cold return water would cool the boiler quickly
the pump would turn off.
the hot water from the first cycle would be pumped further through the system but would have lost some of its heat

these cycles would keep repeating untill the return temp is high enough to stop it possibly resulting in greater heat loss and slower heat up time

I don't agree, I have had my pump run via a pipe stat on my old boiler (replaced a good few years back) and the boiler wouldn't cool quickly enough to stop the pump once it started, set the pipe stat to 55ºc, I did not do it to achieve anything particular on the startup, but at the time the house wasn't zoned, so used it to over-run the pump when time demand was off and there was till residual heat in the boiler that could be shifted into the house (rather than go to waste and cool in the boiler) but the gain is very small. Never set the stat to below 55ºc as on that final cycle you may encourage condensation in the boilers ferrous interior and rot the appliance.

DGOBS

When my boiler first starts up in the morning it only heats upstairs rads and immersion tank and fair enough once its cold the burner stays on a long time to heat it up to 60-65c , but once its reached temp in the boiler then even though the rads and immersion is still calling for heat the boiler burner keeps going into an on/off cycling mode then (keeping its heat I suppose) and then starts for a while, stops for a while and then starts again soon (so maybe off for a min then on for a minute then off for a minute) I have heard that this cycling on and off is not good for the boiler as it can shorten its life? What does it shorten is it the electrodes and the high voltage transformer because it has to stop and ingnite more than it should, is that what it is? - any ideas how to stop it cycling on and off like this? Thanks

I wouldn't be too worried about wear and tear on the burner for short cycling, the bigger concern is that short cycling is inefficient (like stop starting you car constantly diminishes fuel efficiency, more efficient when driving at a steady pace) but as we are not yet in the realm of modulating domestic sized oil burners, theres not a lot you can do about it. The reason is, when your just firing it for a single zone or maybe even just DHW, your using the full output of the appliance, for instance calling for DHW alone to a cylinder with a maximum input of 2Kw, yet the boiler is outputting 20 or 30Kw depending on the size.

But the boiler has to be large enough to meet the total demand of the house when all zones are calling.

This is where at the moment gas boilers are more efficient as they monitor the flow return temperatures to the appliance, and when they se rapid rises, they modulate the output right down, and try to find to optimum output vs requirement so to stay on constantly at the right demand.
Hence eliminating the start/stop inefficiency.

Oil will move towards this in the future, but there is technical issues they have to deal with, and burners of domestic size may become more expensive as a result. You mentioned 2 stage burners, yes plenty of them about, but most are of commercial size as this is where the benefit lies, and also there is requirement for them on large commercial appliances due to cold shocking of heat exchangers needing to be avoided as it would damage the appliance, hence they need low input startup etc.

And before you ask, blue flame is where the fuel is recycled in the blast tube until it is essentially burned like a gas rather than an oil, this has little or no efficiency gain and only serves to lower NOx emissions to meet EU pollution requirements coming down the line. But will result in cleaner combustion chambers and heat exchangers, leading to less efficiency loss during heat take up on an appliance (IMO) and hopefully to much cleaner oil service technicians!!

dathi

jimf wrote: »

andy I love all your questions and enjoy them to an extent

but would you by any chance dissect the fridge or the washing machine for a change

http://ecorenovator.org/forum/geothermal-heat-pumps/484-homemade-heat-pump-manifesto.html
there you go andy should keep you busy with the fridge for a week or two:rolleyes:

Andy From Sligo

DGOBS wrote: »

I wouldn't be too worried about wear and tear on the burner for short cycling, the bigger concern is that short cycling is inefficient (like stop starting you car constantly diminishes fuel efficiency, more efficient when driving at a steady pace) but as we are not yet in the realm of modulating domestic sized oil burners, theres not a lot you can do about it. The reason is, when your just firing it for a single zone or maybe even just DHW, your using the full output of the appliance, for instance calling for DHW alone to a cylinder with a maximum input of 2Kw, yet the boiler is outputting 20 or 30Kw depending on the size.

But the boiler has to be large enough to meet the total demand of the house when all zones are calling.

This is where at the moment gas boilers are more efficient as they monitor the flow return temperatures to the appliance, and when they se rapid rises, they modulate the output right down, and try to find to optimum output vs requirement so to stay on constantly at the right demand.
Hence eliminating the start/stop inefficiency.

Oil will move towards this in the future, but there is technical issues they have to deal with, and burners of domestic size may become more expensive as a result. You mentioned 2 stage burners, yes plenty of them about, but most are of commercial size as this is where the benefit lies, and also there is requirement for them on large commercial appliances due to cold shocking of heat exchangers needing to be avoided as it would damage the appliance, hence they need low input startup etc.

And before you ask, blue flame is where the fuel is recycled in the blast tube until it is essentially burned like a gas rather than an oil, this has little or no efficiency gain and only serves to lower NOx emissions to meet EU pollution requirements coming down the line. But will result in cleaner combustion chambers and heat exchangers, leading to less efficiency loss during heat take up on an appliance (IMO) and hopefully to much cleaner oil service technicians!!

so it sounds like these outdoor boilers are fitted with 70-90btu Reillo 1 stage boilers whereas maybe they would be more efficient with a 2 stage boiler fitted - but unless I am not looking in right place , I couldnt find a reillo 2 stage domestic light oil burner anywhere when i put into google - so do even reillo do 2 stage domestic burners? - I found an ecoflam 2 stage burner running at 20kw in low mode and 29kw in high mode, these were fitted to the stanley waterford brandon range oil boilers