Heat bank and wood burning boiler. Help and advice on spec please

[Archmoco]

Main problem is I'm buying huge quantities of kiln dried hardwood, I'm burning the text book 5.7kg but I'm only getting 8kw instead of the 16kw, so it's costing me twice the amount. Also I'm still waiting the plumber to come back and fit the immersion so I'm relying on solar thermal and just the stove.

i've spoken to the stove supplier today and they say although the manual said 16kw they say their testing says it should be closer to 20kw.

as previous post I'm investigating a possible issue with not sufficient air supply to the house. The house is new with good airtightness, so this might be one issue. I'm also going to give the boiler a good going over with wire brush as it does have a bit of soot build up

 

[Nostrum]

I take it you have a heat meter installed?

What's the flueing arrangement?

 

[Archmoco]

I have a magnet thermostat on top of the stove, I've insulated twin wall flue so can't attach it to the flue. The thermostat on the top of the stove shows I'm not really getting into the efficient burning zone, however I 'm told this is an issue with boiler stoves as the heat is going into the water. Regarding metering I've the thermostats on the Laddomat and one at the top and one at the bottom of the accumulator tank, and I calculated the Kw by recording the temps.

 

[Worcester]

What's the heat loss calcs for the house? - If this is an RHI / MCS certified system, you should have been given full house / room by room heat loss calculations - the load may actually be greater that you think it is.

 

[Nostrum]

What size twin wall have they used and what size comes off the appliance?

 

[Archmoco]

I've SAP calculations for building control with the heat loss. The system was actually design for a lower spec of house as I greatly improved on all of the U values for each element and I've bettered the air tightness.

certainly with the cost of buying kiln dried wood, and the quantity being burnt, it would be more cost effective heating the accumulator tank via immersion, especially at the moment as the solar thermal is actually doing a good job, and I would only need to heat the top of the tank by 5-10 degrees, to keep it above 60.

i think I need to change the cartridge in the laddomat to say 80 degrees so my 400ltrs at the top of the tank for domestic water will last longer and let the bottom of the tank sit at 45-50 so that I'm maximising the solar thermal. I've the under floor heating set at 35-40, and the solar thermal seems to be pumping 55-58 most days even with cloud

 

[Ermintrude]

50mm 9m long no intake.