My ageing logwood gasification boiler may need replacing in the Summer, so I'm considering various options.
The CH system and DHW, ( plate heat exchanger ) are currently fed from the large 2000l accumulator tank. This bit of the overall boiler set up works fine, and I'd like to leave this bit in situ.
The logwood boiler however could do with upgrading, and as I get older a replacement pellet boiler seems to be worth consideration. I'm familiar with how they work and there appears to be a decent choice albeit EU based suppliers. What concerns me is their suitability for batch burn re-charging of such a large store. I can't seem to figure out if they are technically more suited to slower modulating burning more suited to direct connection to a CH system, simple in out, flow and return.
Burning logwood involves the fast, fierce, recharge burn and I wonder if using this methodology every two or three days but running on maximum with a pellet boiler would be unwise.
Does anyone use a pellet boiler with a large re-chargeable accumulator tank, any info would be appreciated. Suppliers I've spoken to either don't know or recon its OK, but then they would say that.

Thanks Phil, I've serviced my own log boiler for years so the practical side worries me less than the availability of spares. I'd have to go for bagged supply because of space, so more expensive I guess. I did spot a decent used one on Facebook marketplace that may be worth investigation.
I've also recently had a look at the combination log and pellet boilers although so far I'm unconvinced of how two different systems can be successfully shoehorned into one cabinet with both using the same water transfer heat exchanger.

Mechanical spares for the boiler we have are available with a bit of effort, but we bought a boiler that had been removed elsewhere ( found for me by someone on gbf in another thread) that has many of the less likely to need replacing and so expensive spares on it if needed. Temperature probes i ordered from europe and weren’t too dear ( no doubt someone who understands such things would be able to source a suitable replacement in uk), the electronics would likely be the bits that possibly would be problematic , they would need to come from the polish supplier.
For some sort of comfidence in support and spares , i’d probably be inclined to look at the established austrian manufacturers that also do commercial boilers. At the time Froeling ( not sure on spelling) were the ones that i was leaning towards, but they were horrendously expensive new.
I looked at the combined boilers, but at the time finding an installer willing to supply and install one under rhi/mcs was impossible ( they all wanted to chuck in cheap pellet boilers, which is partly why the whole scheme turned into a disaster for many who had them installed). The ones looked into seemed to work on the basis of a pellet boilers burner pot , feed system and pellet store bolted onto the side of a log boiler , the hot gases then drawn past the log boilers heat exchanger, seemed a sensible approach and no reason why it wouldn’t work. I liked the idea of being able to buy cheap logs for burns you did when convenient , with the pellet burner automatically kicking in for the times it was required. Apparently it was the log burning that meant they were problematic under rhi.
Pellets by the bag are in a way more convenient, delivered by the pallet and in 10kg bags easy to handle. But pallet delivery soon adds around ÂŁ80 ish to a tonne of already expensive pellets. But if only burning a couple of tonnes a year to make the work of batch burning logs less onerous, the expense is maybe worthwhile.
Mums boiler has a 140kg hopper, in summer for hot water only that would last 1-3 months depending on how many people are there, in a cold winter as little as 2 days if the log stoves aren’t used. We keep a tonne in bags , just in case there are problems with the feed auger from main pellet store, innthe early days we had issues with bridging and learning the position needed for the baffle plate, a couple of occasions where there were bits of bulk bag in the pellets that bound the auger up and the crash mat ( sits infront of the pellet fill inlet to stop the incoming pellets hitting the other side of store and being shattered) gave up the ghost in year 7 and worked its way down to block the pellet outlet.
Finding a combined log/pellet boiler secondhand may be a bit of a challenge, have you space for and sufficient additional ports on your tank to run a seperate pellet boiler in tandem, it’d also give redundancy if issues with either boiler. Plenty of circa 20kwh pellet boilers turning up on the auction site over time.

Posted By: owlmanThe A2W pumps don't appear to reach the temps to charge a buffer tank.

When I move to a heat pump my plan is to run the system without a buffer tank with the heat pump supplying the rads direct or at most very small one just enough to prevent short cycling.
I have collected some data on my current system and in January(s) I can heat the houses with a flow of 55 - 60 deg. with the CH pump running 7 - 12 hours a day so my guess is that an A2W HP would cope with a flow temp of 55 deg. in the cold months which should be doable.

DHW is still an open question, either stay with my summer option all year around (direct immersion heater) or supply from the HP. I'm tending towards the summer option because of less complexities and I have enough PV to cover my annual kWh demand.

Wot about A2A to get away from burning stuff - especially processed stuff AKA pellets