Controling oil boiler with pipe stats

[Brandon]

I would also avoid heating the store with oil, the only reason that I would would be in order to allow a DHW coil tyo be used if one is fitted.

If you have no need for the DHW coil (ie an s plan or such like further own the system) then I generally put a 3 way diverter on the flow from the accumulator into which I put the flow from the oil boiler, the heating control calls for heat, the stat in the top of the store either allows the heating to draw from the store, or throws the 3 port, and lights the boiler.

Cheers

Brandon

[Scotch]

Hi Brandon,
I have two DHW coils in the accumulator tank fed by mains water. One at the bottom to preheat and one at the top then into the house. So I need the boiler to heat the tank to provide both heating and hot water.

However I would be interest to know why you would avoid heating the store with oil?

Thanks for your feedback

[Solal]

Page 13  shows  how  to wire  twin stats also....
http://tiny.cc/o6kcq

[Brandon]

the cost of the oil!

[lightfoot]

Further to what Brandon has mentioned - The 1500 litre accumulator/thermal store is sized to accommodate the output from the log batch boiler, so that it can burn efficiently and provide stored heat for use between firings etc.  But a oil boiler can be fired on demand, so you would normally only need to load the upper third or quarter etc, as and when required, rather than load the entire store - which is not a problem if the boiler is connected directly to the store and controlled by a suitably positioned stat(s), or the return to the oil boiler can be connected higher up the store etc.  Depending on how/when you wish to use the oil boiler, it may not necessarily need to heat the store to 80 degC, as long as it's not adding cooler water to the top of the store (which would upset the stratification etc) and you may need to use a suitable loading valve depending on the minimum store/return temperature and the temperature rise across the boiler etc... http://laddomat.eu/index.php?sida=spartips_laddomat&lang=en

Good luck,

LF.


PS, I assume you have a constant temp/compensating mixing valve on the supply to the UFH/Rad circuits?

[Scotch]

Hi Brandon,
Yes of course cost of oil. However just to explain how I intend to use it. When i said i have my oil boiler as back up, it will only be used if i happen to be away and my wife is at home. If I am at home then all heat will be provided by the log boiler. Ideally I am hoping that the oil boiler will be used maybe only one or two weeks a year. I have been using the log boiler for 18 months now and have managed to source all the wood for free, so i don't mind using the oil boiler for a couple of weeks a year.

Hi Lightfoot,
Good point regards positioning of connections to heat only top third or quarter, however the connections that were let after the install of the tank are top and bottom. I have run the boiler without the stats just as a trial and the top and bottom temps increased at same temp so it wasn't loading as well as it does with the log boiler and laddomat, but again it is only for a short period during a year so I'm not too concerned. My thinking is if i don't let the tank get too cool then the boiler can bring it up to temp fairly easily.
For my heating circuit there is a Thermomatic K mixing valve.

Thanks all

[Scotch]

Well relay arrived, electrican has wired it in and it seems to be working as planned


As we are only using DHW at the moment it takes a few days to see if the oil boiler automatically starts okay. Have been experimenting with temp setting on stats and I actually have both at 60 degrees. Setting the bottom at 60 seems to get bottom tank temp gauge to 80 degrees.
What I have noticed because flow from oil boiler is just above the laddomat and not direct into the tank, heat also travels into the boiler. Which is a bit of a waste however it will give frost protection to the log boiler in the winter.

Attached a picture showing the system with the stats fitted.

Alan,
Thanks for diagram and relay supplier.