Oil boiler with biomass and accumulator

[Barnman]

I have a log boiler that heats an accumulation tank. This then feeds the underfloor heating and a separate pressurised hot water tank that provides the domestic hot water. This all works quite well. However I want to add a backup oil boiler to the system to cater for times when I cannot load the log boiler. As far as I can see there are two ways of doing this. The first is to heat the accumulation tank. This could be done in parallel or instead of the log boiler and the ufh and hot water would continue to operate in the same way. Th downside is that the accumulation tank takes a while to heat and there is an amount of heat loss because of the tank and the pipes from the boiler room to the house. I would also not be able to use solar or heat pumps to heat the tank as the coil would be taken by the oil boiler. The second way is to feed the oil boiler with the water from the accumulation tank. If the water is hot then the oil boiler would presumably not ignite and the water would pass straight through. If the water was not up to temperature then the oil boiler would heat the water.

Has anybody got any views on the best way to do this or any other suggestions.

Thanks

 

[Hugh Jaleak]

I'm not an expert on your type of system, but from previous inquiries of a similar nature it might be worth looking at these: http://www.dunsleyheat.co.uk/neutralizer.html

 

[Mike2007]

Always best to stick with the original design layout as that was the master plan! Using the existing spare tappings and heating the store is the best option really, but you could add the boiler elsewhere. This would add more head aches on the wiring front, as the stats are centered on what the store is doing at any time of the day. You could splice the oil boiler in on the ufh/ dhw cylinder primary pipework, adding zone valves on flow and return pipes. The oil boiler program starts, zone valves close (between store and dhw cylinder, leaving store cut off), boiler and new circulator starts. Hope that helps.