Condensing Boiler

[lattin]

Hi guys, I installed an oil condensing boiler during the week, Working fine. I was wondering what are the savings made with this type boiler. Its a 90 / 120 Btu. Or how more efficient are they

 

[SJB060685]

You say you installed it, is this a DIY install? Different makes of boilers have different overall efficiencies, however a modern condensing oil boiler will be around 10% more efficient, however that largely relies on the system design as well.
What brand of boiler is it?

 

[lattin]

You say you installed it, is this a DIY install? Different makes of boilers have different overall efficiencies, however a modern condensing oil boiler will be around 10% more efficient, however that largely relies on the system design as well.
What brand of boiler is it?

Grant Euroflame

 

[exedon2]

Cheaper cased vortex boiler for Irish Market.
Properly installed/commission by Grant registered engineer?

 

[John.g]

Should be able to get that 10% without trying too hard, My SE (non condensing) firebird has a flue gas temperature of ~ 330C, if I installed a condensing which I prefer to call High Efficiency (HE) boiler as they rarely condense but because of the extra heat exchanger then I would expect a flue gas temp of ~ 100C and as each 100C lower temperature results I think in around 4.5% saving then 10.5% in this case. You can obviously get lower but I think Grant specify 40/45C minimum boiler return temperature so maybe just able to achieve a little condensing benefit as the flue gases will probably be 10C higher at around 55/60C.

SJB or exedon2 might post flue gas temperatures on SE & HW oil fired boilers that they serviced.

 

[lattin]

Boiler is Vortex, u say cheaper model for Ireland, is it a different spec

 

[exedon2]

Assuming it's set up mid range you would expect flue gas temperature of 85-90C C0 2 (%) must be 12.5
Return minimum 45C max 55C to stay condensing. Grant recommend a 20C temperature differential

 

[SJB060685]

Should be able to get that 10% without trying too hard, My SE (non condensing) firebird has a flue gas temperature of ~ 330C, if I installed a condensing which I prefer to call High Efficiency (HE) boiler as they rarely condense but because of the extra heat exchanger then I would expect a flue gas temp of ~ 100C and as each 100C lower temperature results I think in around 4.5% saving then 10.5% in this case. You can obviously get lower but I think Grant specify 40/45C minimum boiler return temperature so maybe just able to achieve a little condensing benefit as the flue gases will probably be 10C higher at around 55/60C.

SJB or exedon2 might post flue gas temperatures on SE & HW oil fired boilers that they serviced.

I can't post pictures because I've been off work for some time but your above post pretty much sums it up. Also like exedon2 mentions oil condensing boilers need a minimum return temperature so the water flowing through the primary heat exchanger is too low a temperature and cause corrosion. This largely depends on the efficiency of the secondary hex and how much latent heat it's able to withdraw.

 

[John.g]

Are all condensing boilers, both gas&oil, efficiencies expressed; based on the net calorific value of the fuel and if so, why?.

 

[SJB060685]

Flue gas analysers are calibrated for certain fuels and they know the characteristics of each fuel. However combustion efficiency is calculated by measuring the CO² and flue gas temperature, from this it works out the gross and net efficiency.

 

[John.g]

Not sure where I picked this up but it does show a very low flue gas temperature, presume the boiler was allowed sufficient warm up time.

 

[SJB060685]

Not sure where I picked this up but it does show a very low flue gas temperature, presume the boiler was allowed sufficient warm up time.

Dated 16 of June last year, so a reasonably recent service.
Figures look good.
When commissioning a burner it should be set up from cold but usually the burner will have been running 10-15 minutes.
Also when commissioning a new install the burner is loosely set up and then the technician returns two or three days later to set up properly once the boiler has had a chance to burn off any impurities from construction, otherwise your readings would be all over the place.
The flue gas temperature of 56°c suggests the boiler is condensing nicely.
The CO² % is an indication of the level of combustion, so I higher CO² % and lower flue gas temperature = greater efficiency, however you always have to allow a certain amount of excess air for complete combustion. The CO ppm is acceptable though.