Heat meter readings for vigas biomass boiler

[cornish wood burner]

Hi Cornish wood burner. Thanks for the input. The reason I mentioned that the fan is working hard all day is to get across that the burner is loaded many times a day, and is gasifying all the time. We have a large heat load, and if left without burning, the accumulator tank soon gets dragged down. We sell a lot of firewood ourselves, and the fuel we use is all the softwood and poor quality hardwood that I don't wish to sell. However, it is very dry, having been dried in poly tunnels beforehand, and is always below 20%. Because of what I burn, I accept that I am loading more often than burning hard wood, but will still expect more kW / day. Regarding siting of heat meter, the boiler room is about 75 m from the house. I actually have an 80 kW and a 100 kW sited together, both running into the same tank. The 100kw is currently rarely used, but was installed to make use of the tariffs when they were better. I hope to install a kiln in the near future using the 100kw for the heat source. Because the 2 boilers are on different tariffs, they each have there own meter which records there output into the tank, and the 2 demands on the tank, ie our house and the workshop / office, each have another meter, so we have reasonably good records of what heat comes from each boiler and where it goes. We do suffer heat loss from the heat main, but only a small amount, no more than you would expect. The low readings stem from the meter sited only a couple meters from the boiler, before it goes into the tank.

 

It sounds like you would have been a prime candidate for a chip boiler. I normally run our RHI chip boiler at about 80% capacity. However I can get the rated output 24 hours a day if necessary but run lower to improve efficiency and longevity.

I can imagine keeping your boiler topped up is bit of a chore. Feeding it with 25 kg of wood per hour to get your 80 KW must almost be impossible. The problem with any boiler is continuity of supply. Without it you have no chance. Our big chip boiler (non RHI )has a flawed feed system and suffers a visible big drop in output because of it.

Unfortunately there is some very poor advice and design out as we have found over the years. I now do not trust any salesman or system design and always do my own calculations on it. We have turned down many more than we have approved.

[Duncansimpson]

Presumably you mean 380 KWh per day so assuming your boiler is 80% efficient and your wood is 20%MC then that is about right.

 

 

Thanks for working that out for me! I was told I would burn about 30t a year but we always use more. I do keep it cranked up especially in the winter.