sf 250 domestic hot water set up

I think I have read every post on here about domestic hot water coil setups. I think I have it figured out. I need one more piece to the puzzle to complete the install. It's a hot water unit that I can put in the circulation loop to control the heat, what I mean is something working on the same principal as the radiator and electric fan on your cars. The water will be constantly circulating through the stove, tempering tank, and whatever unit I can find to control the water temp. Can anyone tell me what I need and where to get it?
Thank you, Craig.

Not sure, but I'm thinking heat sensitive or thermostatically controlled valve, installed in a bypass loop. ... when the water gets up to temp., the valve opens and bypasses the heat exchanger coil.

Hello Craig. Actually you don't want to stop the circulation of the water in the loop. If you do, then you will have stagnate water in the loop sitting over the 1500*+ fire, and it WILL boil, make steam and pressure, and make your PRV open.
Your stove will be running, making heat, the loop will always be above the fire, collecting heat. You can't stop the loop system from collecting heat
What you want is to keep the water circulating, this keeps the above from happening, but if you fear that you will get the domestic water too hot, then you need to put an additional circuit on it to 'dump' the excess heat into a section of baseboard heating unit, or into a below floor radiant heat system..

So if you have excess heat, then use it where it will do you some good.. You can't control the fire automaticly in a SF stove, and you can't stop circulating the water, so the only other choice is to use the excess heat.

Greg L

Thanks for responding' Your right I don't want to stop the water from circulating and I do want to put a section of baseboard or something similar. It has to have a fan built on it. 'With the water constantly circulating' and the fan set on an aquastat to kick on when the water gets too hot. Like I said on my original post, the same principal as the radiator,and electric fan cooling unit on all the newer cars. There has to be something. I just don't know what it is called.

Hi, It would be a good time to put a loop of heat in the basement. Modine (model HS/HC 18) makes the unit your looking for. I just put one in my brother's garage. It wouldn't cost that much and if your floor joists for the first floor aren't insulated. It will heat up the floor some too. Just a thought. Seeing as you will have no control over the boiler dumping heat.. I used the HS24 it was about $400.00 at a plumbing supply house.

Pete..

Thanks repete I'm going to try and find something on the modine sight. I know from reading all the posts on here it's going to make the water to hot and pop the prv, the loop in the basement is exactly what i had in mind, although it should already be plenty warm with the sf 250 cranking, my main objective is to set up a cooling system to control the water temp.
The building I work in is heated by a big old Gentleman Janitor coal furnace (it's a big building) it is hot water heat. When the thermostat calls for heat the circulator pumps water to these big coiled fin things hanging from the ceiling( they look similar to a truck radiator) when the water going through these things is hot enough, the fan that's built in them kicks on and blowes the warm air throughout the building. The fan turns off when the water isn't hot enough. This is what I want my setup to do, minus the thermostat controling the circulator. Thanks for your reply Craig.

Wouldn't a mixing valve work to control the temp coming out of the faucet?

Hi trader, the problem would be that a SF250 is a BIG handfeed stove, and it will make lots of heat during the day or all night when there is no use of domestic water,, so the tank probably would get to the boiling point... So what is needed is a 'close on rise' snap disc temp switch that will start a circulating pump and maybe a fan in a water to air heat exchanger or air heating unit, so that the 'heat dump' will start once the temp of the water exceeds a desired limit..

It's been done lots of times, it isn't dificult.. Just takes a plan.

We really need to know more about the location of the stove, open floors above, location of dumping heat when needed, etc.. More info= better suggestions and ideas..

greg L

The stove will be installed in the basement of an old farm house, about 2600 sq ft. The stairway is open, I will be installing at least 2 cold air return registers, it doesn't really matter where I put the water to air heat exchanger as long as it serves the purpose of controling the water temp. Oh and from reading all the posts on here it seems the water has to be circulated constantly so the switch only has to control the fan. Thank you for your reply, Craig.

It looks like there are a ton of valves, thermostats, sensors, etc. for radiant heat operations. In addition, there are a number of clever ways to use radiant heat, which might lend themselves to your situation.

example: http://www.pexsupply.com/CategoryPre.asp?cID=297&brandid=

Thanks for all the help, I have found a unit heater fan made by modine that will work with a reverse aquastat. My next question is where in the circulation loop should the heater fan be? Should I put it on the inlet side of the tempering tank where the heated water exits the stove or should it be on the return between the tank and the stove? Thank you Craig.

I'm thinking, the aquastat should be in the top of the tank, to regulate the tank contents temperature. Once the tank has reached the preset temperature, then you wouldn't want any more heat in the tank, so ... I'd go with the dump between the stove and tank input. :?: (of course, that is subject to change, if it sounds really dumb, later.)

Kinda like >>>

Yep that is what I thought too,The attachment you included showes the aquastat controling a valve, from reading all the posts on this sight reguarding this application I do believe there has to constant water circulation through the tank and stove to avoid boiling the water, for that reason I want the reverse aquastat to control the fan on the unit heater. Now on to my next question. What temp are prv valves set to open at, and what would be the proper setting for the aquasat? Thank you Craig.

pa coal cracker wrote:The attachment you included showes the aquastat controling a valve, from reading all the posts on this sight reguarding this application I do believe there has to constant water circulation through the tank and stove to avoid boiling the water, for that reason I want the reverse aquastat to control the fan on the unit heater. Now on to my next question. What temp are prv valves set to open at, and what would be the proper setting for the aquasat? Thank you Craig.

I forgot to include the pump in the diagram ... fixed it . The water doesn't have to flow through the tank continuously, but it does have to flow through the coil continuously. So, the "closed" valve would allow it to flow through the "coil/tank" only OR "open" valve would allow flow through the "coil/fan heater" ...and maybe a little bit through the tank, as I have it drawn.

I've forgotten what temps the PRV are, but if you have one on the tank, it should be OK. The aquastat should be set at the normal setting of your high limit water ... 120* ... I forget what we are supposed to have here.

You probably would want the aquastat to control the fan/heater operation, as well as the valve. The other valve option, might be a "two way diverter valve", at the junction of the inlet to the fan heater and the pipe to the water tank, instead of the one I pictured. ... controlled by the aquastat