Hi Mars,

It all depends how efficiently your boiler is at extracting the energy from the fuel. if the calorific value of the fuel indicates that 1 litre contains 10.35 kW of energy, but your boiler is say 80% efficient, then the actual useful energy produced would be 8.28 kW per litre. So if your boiler produced 63.6 kWh of heat energy, then the fuel consumption should have been approximately 7.7 litres.

@derek-m, ah, that makes. During the boiler modifications, they ran the tests and the boiler was showing an efficiency of around 95% – but I did't take the efficiency into account, which makes perfect sense. I will keep an eye on things, but the house is heating well. It seems like it's a really good fuel at this point. 

@editor 

how does the price and availability compare with kerosene? I wonder how your ASHP would have compared in running costs?

Kev

@kev-m, all great questions, and this is exactly what I'm working through. The HVO isn't, as far as I'm aware, available yet to homes as a heating fuel and we're on an OFTEC trial to test the fuel on a bivalent ASHP system. So far so good. Im awaiting costs from OFTEC next week - once we get all the info we need, we'll put everything together and share it. Initially, it's a great "green" fuel for off grid homes that are running on kerosene.

Trying to get my head around oil boilers - it's so much easier to mange things like heat pumps.

I'm trying to work out how much HVO fuel we've used – our heat pump says that we used the oil boiler for 6.85 hours on one of the days. My question is do oil boilers have a "standard" figure to know how much fuel they'd burn through in an hour?

@editor Do you know the size of the oil nozzle? this should give you an idea of the flow rate the boiler is cable of. As an example, the Danfoss oil nozzle 00.55 x 80 gives a flow rate of

0.55 US gallons per hour. 

@prjohn, thanks for that. I have the boiler popping around this afternoon so will ask him, but the 0.55 gallons per hour (about 2 litres) is a useful starting point.

Posted by: @editor

@prjohn, thanks for that. I have the boiler popping around this afternoon so will ask him, but the 0.55 gallons per hour (about 2 litres) is a useful starting point.

@editor

I looked up some figures from our oil boiler spec. which might be useful for comparison. For the specified nozzle size, the oil usage rate is dependent on the oil pump pressure. So in our case, at 145 psi, the flow rate is stated as 3 L/hour, while for a setting of 110 psi a flow rate of 2.72 L/hour is quoted. I have been keeping reasonably accurate and regular readings of our oil usage over the last couple of years by dipping the tank. I have estimates of the usage in litres/week and the controller on durations, but not the actual burn times. However a rough estimate does give very similar oil use rates in L/hour.

One thing that confuses me is the boiler efficiency. The last service sheet quotes an efficiency of 97.9% and a previous one 99.9%. I believe that these are Net efficiency figures. There is another way of measuring efficiency, Gross efficiency, which is less than Net. Another service record quotes both at 97.4% Net and 91.6% Gross. My understanding is that Net efficiency excludes the latent heat that goes out the flue and hence that Gross efficiency should be used, but I may have that wrong.

Posted by: @editor

@kev-m, all great questions, and this is exactly what I'm working through. The HVO isn't, as far as I'm aware, available yet to homes as a heating fuel and we're on an OFTEC trial to test the fuel on a bivalent ASHP system. So far so good. Im awaiting costs from OFTEC next week - once we get all the info we need, we'll put everything together and share it. Initially, it's a great "green" fuel for off grid homes that are running on kerosene.

@editor

Thanks for this useful information, I wasn’t aware of this fuel. Regarding it’s green credentials, it appears to be derived from waste vegetable/animal oil but how is the hydrogen generated for the hydrotreating process, is it derived from renewable energy?

Looks like there are other trials underway, according to the trade association and fuel suppliers websites. Might be a good stopgap, but are not new oil boiler installations to be banned from 2025?

@rusty, we just filmed our first impressions video today about using HVO. So far, it's been really good.

You've raised some excellent points – we're on the trial for six months and are dealing directly with OFTEC on this one, so I'll try and get some answers on the use of hydrogen in its production. I think there are a going to be a lot of loopholes surrounding oil boilers for off-grid properties but I'll try and get answer on this one too.

Posted by: @editor

@rusty, we just filmed our first impressions video today about using HVO. So far, it's been really good.

You've raised some excellent points – we're on the trial for six months and are dealing directly with OFTEC on this one, so I'll try and get some answers on the use of hydrogen in its production. I think there are a going to be a lot of loopholes surrounding oil boilers for off-grid properties but I'll try and get answer on this one too.

I think you will find that the Hydro actually refers to water rather than Hydrogen.