Tec question on rocket stoves

CNM Design · 02-11-14, 02:37 PM

I have a hot water boiler system now. Baseboard radiant heat. Will be changing to in floor later.

Max temp is 180, minimum is 120 and then the gas kicks on.

Circulating pump runs 24/7 so not to let the left over heat in water go up the flu when pump is off.

Gas does not run 24/7.

Stove must run 24/7, can not turn off and then back on when heat is called for.

Am I correct in assuming my over all goal is to keep the temp in the gas boiler from dropping below 121?

Second goal is to find the btu out put from the stove required to maintain a water temp in the gas boiler of at least 125 or 130.

I think pumping 125-130 24/7 should be ok.

Third goal would be to determine a flow rate for the fuel (pellets) and then design a feed mechanism capable of sustaining that rate.

If for some reason the fire goes out or fails to provide the btu’s required to maintain 120 in the gas boiler, the gas boiler will take over.

Is it all this simple or am I missing something?

Can’t see myself building a stove just to build a stove. Need goals and requirements first.

Could mean the difference of several thousand btu’s in fuel cost a month.

jeff5may · 02-11-14, 05:19 PM

What you are looking for here is a PID controller. You should be able to control the feed rate of pellets into your stove, and thus, the resulting BTU output, after a time lag. You can set it to maintain a near constant temperature of something. That something is up to you.

How you exercise control depends on the purpose of your boiler. If, if, and if is the word here. If it provides only heat, it will work one way. If it also provides DHW, it will work different. If constant water temp is your goal, the system will work differently than if constant room temp is desired.

Please elaborate on details of what you want out of the system and what the home is like. More details helps keep the speculation down.

02-11-14, 02:37 PM	#1
CNM Design Lurking Renovator Join Date: Feb 2014 Location: S.E. OHIO Posts: 5 Thanks: 3 Thanked 1 Time in 1 Post	Tec question on rocket stoves I have a hot water boiler system now. Baseboard radiant heat. Will be changing to in floor later. Max temp is 180, minimum is 120 and then the gas kicks on. Circulating pump runs 24/7 so not to let the left over heat in water go up the flu when pump is off. Gas does not run 24/7. Stove must run 24/7, can not turn off and then back on when heat is called for. Am I correct in assuming my over all goal is to keep the temp in the gas boiler from dropping below 121? Second goal is to find the btu out put from the stove required to maintain a water temp in the gas boiler of at least 125 or 130. I think pumping 125-130 24/7 should be ok. Third goal would be to determine a flow rate for the fuel (pellets) and then design a feed mechanism capable of sustaining that rate. If for some reason the fire goes out or fails to provide the btu’s required to maintain 120 in the gas boiler, the gas boiler will take over. Is it all this simple or am I missing something? Can’t see myself building a stove just to build a stove. Need goals and requirements first. Could mean the difference of several thousand btu’s in fuel cost a month.

02-11-14, 05:19 PM	#2
jeff5may Supreme EcoRenovator Join Date: Jan 2010 Location: elizabethtown, ky, USA Posts: 2,431 Thanks: 431 Thanked 619 Times in 517 Posts	What you are looking for here is a PID controller. You should be able to control the feed rate of pellets into your stove, and thus, the resulting BTU output, after a time lag. You can set it to maintain a near constant temperature of something. That something is up to you. How you exercise control depends on the purpose of your boiler. If, if, and if is the word here. If it provides only heat, it will work one way. If it also provides DHW, it will work different. If constant water temp is your goal, the system will work differently than if constant room temp is desired. Please elaborate on details of what you want out of the system and what the home is like. More details helps keep the speculation down.