Aquastat Needed or Not ?

[RJP Electric]

Is this true,
My plummer said when the biomass is charging the tank it will keep circulating until the water returning is hot and it will satisfy the wood boiler and shut it down.
My circulator will be connected to the RK-2001U controller. Should I use an aquastat also in conjunction with the controller? If so where should it be located and how should it be connected?

Here are some installation pictures , radiant zone being added too.

Rob

 

[Nofossil]

In my opinion there are a couple of possible problems.

One is that as the fire starts to die down, you don't want to circulate if the boiler isn't hotter than the storage. Most boilers will shut off when the outlet temp drops below a certain temp. If your storage is hot enough, heat from storage could keep the boiler circ running for a long time after the fire had died.

 

[RJP Electric]

Ok I understand your reply. So how does the aquastat come into play to prevent that ?

 

[Nofossil]

Without a plumbing diagram, it's nearly impossible to answer your question. Do you have a fossil fuel backup heat source? How are heat zones controlled? Too many different ways of doing things to have a single answer.

It may be that the easiest solution in your case is to make sure you never build a big enough fire to get the bottom of your storage tank above 150 or so.

 

[RJP Electric]

You have seen this before with a few modifications done to it. The reason for those zone valves is self explanatory,they operate with the pumps to assure optimum flow and diversion. I have some heat loss through the oil boiler but that is fine.

Now how does an aquastat come into play to prevent the circulation of already heated tank water back to the biomass for after the fire had died if controller is used? The controller will turn on the circ when overheat. If I just need a aquastast on the return of the tank, and one on the supply of the wood to prevent overheating to turn on the circ that will be fine too.

What are other people doing with pressurized storage


Rob

 

[Nofossil]

This is an interesting issue. Might be worth running for a while and see if it becomes a problem. You say your controller will turn on the circulator on an overheat condition - does it normally turn it on only when there's demand? If that's the case, then an aquastat near the bottom of storage could generate a demand signal for water temps below 150. Above that, the biomass circ would only run on overheat.

 

[RJP Electric]

Yes I will give that a shot, sounds like a good idea. Thanks!