Do I need an aquastat for storage

[woodsmaster]

This probably a dumb question but here goes. Do I need an aqua-stat for my storage tank ? I have an rk 2001u controller. The boiler has three wires out the back, one for the fan, one for circulator, and one for power.
Looked at the wiring diagram but didn't really say about storage. If one is needed how would it be hooked up?

 

[ewdudley]

This probably a dumb question but here goes. Do I need an aqua-stat for my storage tank ? I have an rk 2001u controller. The boiler has three wires out the back, one for the fan, one for circulator, and one for power.
Looked at the wiring diagram but didn't really say about storage. If one is needed how would it be hooked up?

Normally it's assumed that the boiler should feed hot water to storage constantly until it is out of fuel or until the boiler temperature maxes out. So normally you would jumper terminals #3 and #4 so the boiler runs flat-out, which means you don't need any feedback from the storage system. [Edit: Just to be clear, yes you can definitely make good use of a storage tank aquastat in the system as pointed out below, but no the storage tank aquastat doesn't normally participate in controlling the wood boiler.]

Usually the jumper across terminals #3 and #4 is installed before delivery of the boiler. Look close, it could be a fine wire. If the boiler runs in 'F' mode then the jumper is there.

--ewd

 

[Chris Hoskin]

we use a tank aquastat (open on rise) to tell the fossil fuel boiler that it needs to come on because the tank temp has dropped too low to heat the home. Or, put the other way, the tank aquastat keeps the fossil fuel burner locked out until the tank is depleted.

 

[woodsmaster]

Thanks that answers my question.

 

[in hot water]

A differential control works well also. This allows the pump to start when the boiler is warmer than the tank, and off when the tank gets within a set temperature of the boiler.

With an aquastat the pump can continue to run after the fire goes out, that may not be ideal, as it will cool the tank and allow heat energy to go up the flue

A solar, or differential control with a minimum start temperature is ideal. I have mine set at 150F. So the boiler warms to 150 before the pump can start and stops when it drops to 140F or lower. Many of these controls have variable speed functions so the pump speeds up as the boiler gets warmer and slows as the boiler cools, This eliminates some pump cycling and uses less energy when the pump speed is reduced.

hr

 

[RobC]

Another fix for controlling the boiler pump, to shut off, is to have it wired to a relay ( I use a RIB ) and have pump controlled by the blower fan. Fire out / blower shuts off / pump shuts off.

 

[flyingcow]

Another fix for controlling the boiler pump, to shut off, is to have it wired to a relay ( I use a RIB ) and have pump controlled by the blower fan. Fire out / blower shuts off / pump shuts off.

Thats how my unit is set up. i used the loading valve that tarm had in their plan. Stack temp 90c, fan shuts off, circ shuts off. The only aquastat i have in the storage tank is wired to the BLT controller. Set for about 110, tank gets colder than that, kicks in the oil boiler.just as tarm sales guy stated.

 

[woodsmaster]

So if I don't add some sort of controller the boiler pump will run after the fire is out ?

 

[RobC]

Woodsmaster, looking at the online material all I can see is you have a newer controller with your Boimass. Including a variable speed fan. Your controller may already do circulator shut down. Maybe call New Horizon and ask ? Looks like a nice unit !

 

[ewdudley]

So if I don't add some sort of controller the boiler pump will run after the fire is out ?

Your RK-2001UA is programmable to shut off the circulator and the draft fan after the boiler temperature has remained below the boiler setpoint minus hysteresis for a certain amount of time. The manual is not so easy to make sense of (and I'm not so sure I'm doing any better), but study the 'No fuel' section of the manual and review the service parameter discussion and it should make some sense after a while.

--ewd

 

[flyingcow]

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