Mon, 25 May 2026 13:08:15 +0100 https://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1665&Focus=19795#Comment_19795 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1665&Focus=19795#Comment_19795 Thu, 01 May 2008 19:26:27 +0100 Jeff B
We are scrapping our existing combi oil fired boiler and going over to a wood pellet boiler with thermal store. The latter will also have tappings/coils for solar (for immediate connection) and air source heat pump (for possible later addition). Currently the combi oil boiler is located in a small boiler room which is located more or less in the centre of the ground floor of our dormer bungalow. There will be no room for the wood pellet boiler and hopper in the boiler room, so we thinking of two scenarios:

1. Locate the new boiler/hopper in the garage and put the thermal store in the boiler room. This way the hot water pipework to the various taps around the house would be fairly short runs (minimal heat loss) but the flow pipework from the boiler and the solar panels to the thermal store would be relatively long (larger heat loss).

2. Alternatively the thermal store could also be located in the garage, so that the boiler and solar panels are in close proximity to the thermal store (minimal heat loss from the flow pipes) but then there would be long runs to the various taps (larger heat loss). Note: the solar panels are going on the pitched roof of the garage, which is at one end of the property, and thus would be quite close to the thermal store.

Which of the two scenarios would be best from a prevention of heat loss point-of-view, or in reality would it make no difference either way, provided all the pipework is adequately insulated?

Any advice greatly appreciated.

Finally any suggestions regarding choice of wood pellet boiler? We seem to have narrowed the choice down to Gerkross, Scotte or Ashwell.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1665&Focus=19796#Comment_19796 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1665&Focus=19796#Comment_19796 Thu, 01 May 2008 19:47:51 +0100 nigel
http://www.windhager.com/FireWIN.96.8.html]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1665&Focus=19818#Comment_19818 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1665&Focus=19818#Comment_19818 Fri, 02 May 2008 09:35:30 +0100 Mike (Up North)
The Winhager is a nice unit. It can if you wish come with a pump / exp vessel etc integral with the casing etc so it would pretty much just hook up into an existing conventional CH/DHW system, and it does have a vacuum delivery hose for the pellet supply from upto 20m away. It also has a piped air feed for the 1st & 2nd stage burn so effectively its “room sealed” so there are no open flues or air supply issues. Another good point is there is thick steel plate that can be slid up from within the door which blocks most of the radiated heat. This means the unit can operate as a boiler with very low heat to the room which is better for summer operation. Nice bit of kit.

You say taps – I assume you mean taps and heating supply tapings from the store?

However, for the set up you describe a pellet boiler (not a pellet stove) would always be in a “boiler house” or basement or garage as they are not as clean or quiet. They will give off quite a bit of lost heat so that is a shame. Either way the pre-insulated pipe for these sorts of applications is very expensive and will loose more heat than expected.

I assume the garage is not attached to the house?

Option A is simpler as there would only be a flow and return pipe between them boiler – store (garage), then various tapings off of the store at the house for water/heating.

Option B would need either many pipes from the store (gargae) or some sort of manifold / header at the house end for distribution (preferable).

BUT The accumulator (500 -1000 lit ??) normally needs to be adjacent to the boiler because when firing is complete there is still considerable heat within the boiler. This is usually shunted on into the tank by pump overrun, which means that a temp sensor at the boiler will make the pump push hot water over to the tank after the fire is out until the boiler water jacket comes down to a lower temp, otherwise you get localised boiling/scaling deposits within the boiler. BUT if there is a power cut, and if you were burning say logs (I know your not) which would continue to burn for 5-6 hours, the heat needs to pass to the accumulator by gravity/thermal siphon. That’s why they don’t usually do “up and over piping”, or “down and under” piping. Devices that control the boiler feed temp (in order to maintain high flow temp) such as Laddomat 21/ Termovar loading valves have a one way valve within the body, and these units must be horizontal and down low so as to allow self circulation in the event of power failure. In principal a pellet unit would burn out on power failure as the delivery auger would stop. The question is how long would the fire burn for? Still enough heat I think to cause a problem.

Do you have any suggested pellet boilers in mind? It would be well to discuss with the suppliers / manufacturers the option A split scenario as I think they will assume option B together.

Food for thought.

Cheers, Mike up North]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1665&Focus=19953#Comment_19953 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1665&Focus=19953#Comment_19953 Sun, 04 May 2008 17:24:42 +0100 Jeff B
Mike - thank you for your observations. I mentioned the 3 boilers on our shortlist in my post above but I think we will go for the Scotte (now Nordic Bio Energy), based on personal recommendation. I will ask them about the "after-burn" effect during a power cut. I think I prefer Option 1, so your point is important. From what I can see at the moment there are only a very few pellets in the grate at any one time, so hopefully the effect you describe will not be problematic.

The garage IS attached to the bungalow but not integral with it, if you know what I mean. Is this a concern?

You are right about the preinsulated pipework for the solar panels - it is very expensive. (I have been quoted about £14 per metre). It is tempting to go for Option 2 for this reason alone!

Jeff B]]>