Additional heat from wood furnace.

[all night moe]

My Thermo-Control has 2 water coils inside. Originally meant for heating DHW, I'm sure. My thoughts are to use these for a bit of hydronic heat. I'd like to make a loop into a 55gal drum. I have a very clean one, painted inside and out. Will circulate this loop with a Taco 007 on 1'' lines.

2nd loop will be 3/4'' barrier PEX, approximately 150' round trip, into my kitchen. This circulator I'm thinking of a Taco 009 or another 007. The kitchen will have 6' of tube and fin, and then plumbed after that, a water to air HE. Made from more tube and fin. Fitted with manifolds, inside an insulated box with a box fan, and controlled by a thermostat with variable speed switch.

The drum will have return ports 2/3rds up from the bottom and supply ports near the bottom. The ports for these loops will be 180* from each other for good circulation. The 3/4'' bung on top will be for a vent via 4' of coiled copper 3/8 line, enabling drain back. The 3'' bung will be for viewing water level and fill port. Drum will be insulated.

On the loop to the kitchen, I'd like to include a heat dump in the crawl space via water to air HE, should things get to hot. Possibly a large truck heater core, or more tube and fin, cooled with a 8'' desk fan. I'm looking for a bit of guidance in the controls for this heat dump. Aquastat? Researching solar systems for heat dumps, I see some use a 3-way valve.

The kitchen has a ventless LP, wall mounted heater. I'd like not to use this as a primary heat source, rather a booster of sorts. Plan is to let the 6' length of tube and fin flow continuously, and set the box fan sized water to air HE at about 65*. This can be turned up as needed. The hydronics will keep the kitchen from freezing. 4 yrs here and we haven't had continues heat in the kitchen yet. This system is "quick and dirty'' until I get a OWB up and running.

Thoughts, advice, help, and critizim all apreciated.

 

[pettibone]

I made a coil for my woodstove that had to go down to the cellar to hook into our heating system, had a dedicated circulator to pump it through the system. It worked ok until we lost power and no more circulator, instant steam. Guess what I'm saying is if it will flow by gravity without a pump it would be ok but if it doesn't could get exciting.

 

[gthomas785]

Yeah the dump zone w/circulator is good idea but make sure you also have a relief valve. If it's going to be a closed system then you need some kind of expansion tank as well.

I would just set up the dump zone as another zone controlled by an aquastat on the tank set to like 200 degrees.

 

[all night moe]

Yeah the dump zone w/circulator is good idea but make sure you also have a relief valve. If it's going to be a closed system then you need some kind of expansion tank as well.

I would just set up the dump zone as another zone controlled by an aquastat on the tank set to like 200 degrees.

Good thought on the relief valve. I will T of the 3/4'' bung with the copper 3/8 tube coiled above. Open system ....the copper coil is for venting. I can only imagine the horror of pressurizing a 55gal drum. LOL

How do I create a dump zone off my heat load zone? I'd like the dump zone to be off of the kitchen loop so it dumps excess heat into the crawl space. A zone valve....or 3-way valve?

 

[all night moe]

Guess what I'm saying is if it will flow by gravity without a pump it would be ok but if it doesn't could get exciting.

Luckily we rarely loose power, nock on wood.
With the space limitations around the oil and wood furnaces, and the foundation, I don't think I could get it to thermosiphon.
Maybe..... I considered it then thought there'd be to much plumbing and bends to get it to work. There's also an old massive cistern consuming space.

 

[all night moe]

Bump.

Still looking for guidance on components to control the heat dump. I plan on dumping excess heat in the crawl space. The location for the heat dump is about 20' from the drum. I'm assuming I'd want to read temps in the drum.
I'm trying to make a parts list of all the components so I can budget my monies for this project.
Thanks

 

[gthomas785]

I'm not quite sure what you're asking... How would the 3-way valve be piped? I think of a dump zone as just another regular zone that gets activated based on system temperature.

 

[all night moe]

I'm not quite sure what you're asking... How would the 3-way valve be piped? I think of a dump zone as just another regular zone that gets activated based on system temperature.

Not sure I need a 3-way valve. I seen a vid heat dump, in a solar system, using a 3-way valve.

For clarity, lets call my hot water supply zone A. This is from the furnace. Then there is zone B, the heat supply to the kitchen. Both of these zones are separate and have their own supply and return ports to the 55gal drum.

I would like to keep my heat dump in series, within zone B. Letting the hot water flow though the heat dump HE and then to kitchen room HEs. Fan for the heat dump would be activated when temp in barrel gets to hot. Example, on at 190-195* and off at 180*.

I've read somewhere HD was set as a separate zone using a circulator. That would require 3 circulators for my setup. Like I was saying, I'd rather keep the HD in series and just activate a fan. Either way how do I activate a fan, or even a circulator? I think I need to use an aquastat with high and low capabilities? Confusing for me is the 24v/transformer stuff. I somewhat understand but, I'm defiantly green to this.

 

[gthomas785]

I would put the dump zone in parallel that will increase the dumping capacity. You don't need a separate circulator just use the same circulator as for the heating zone and put in a tee with a zone valve. Would your circulator be running continuously or do you have a thermostat upstairs? Wire it so the aquastat triggers the zone valve to open and kicks on the circulator if it's not already running.

 

[all night moe]

I would put the dump zone in parallel that will increase the dumping capacity. You don't need a separate circulator just use the same circulator as for the heating zone and put in a tee with a zone valve. Would your circulator be running continuously or do you have a thermostat upstairs? Wire it so the aquastat triggers the zone valve to open and kicks on the circulator if it's not already running.

Circulator will run continuously. So I just need an aquastat, and zone valve. I think the best way to run this in parallel is to use a pair of manifolds at the supply and returns at the drum. The supply being forwards of the circulator, of course.
Can I use the same aquastat to trigger the heat dump HE fan too?

Thanks for your time and education. Greatly appreciated.

 

[gthomas785]

Circulator will run continuously. So I just need an aquastat, and zone valve. I think the best way to run this in parallel is to use a pair of manifolds at the supply and returns at the drum. The supply being forwards of the circulator, of course.
Can I use the same aquastat to trigger the heat dump HE fan too?

Thanks for your time and education. Greatly appreciated.

Yeah I mean I don't know exactly how you're setting up the controls but if you run 24v through the aquastat to a 24v zone valve then you'd send the same 24v into a contactor to control the fan. If you're using a 120v aquastat and 120v zone valve, then you can just wire the fan in parallel with the zone valve.

 

[salecker]

Usually a dump zone is for when the power goes out and you don't have the pumps running to move the heat.
So the dump zone opens automatically to prevent the boiler from overheating.
If it's operating when you have power then it's just another zone.

 

[all night moe]

Usually a dump zone is for when the power goes out and you don't have the pumps running to move the heat.
So the dump zone opens automatically to prevent the boiler from overheating.
If it's operating when you have power then it's just another zone.

In this configuration, how is the heat dumped? I understand it is a power open/no power closed valve. How is the heat being dumped?
Just curious.

 

[gthomas785]

In this configuration, how is the heat dumped? I understand it is a power open/no power closed valve. How is the heat being dumped?
Just curious.

It would need to be a normally open valve with the ability to thermosiphon. Based on your earlier posts I gathered this was not what you were trying to do, but it's not a bad idea.

 

[all night moe]

It would need to be a normally open valve with the ability to thermosiphon. Based on your earlier posts I gathered this was not what you were trying to do, but it's not a bad idea.

You have gathered right. I would not be able to thermosiphon the heat dump.
Although I have been thinking of doing that with the barrel to wood furnace, eliminating a circulator. I can elevate the barrel above the input to the furnace. Water would still have to travel about 6' horizontally at a slight downgrade to the furnace, and then back of course.

 

[gthomas785]

You have gathered right. I would not be able to thermosiphon the heat dump.
Although I have been thinking of doing that with the barrel to wood furnace, eliminating a circulator. I can elevate the barrel above the input to the furnace. Water would still have to travel about 6' horizontally at a slight downgrade to the furnace, and then back of course.

So in the event of a power outage, the thing that would overheat is the furnace. That's where the fire is. So if you can get a vertical rise directly from the furnace coil to the heat dump, that would work. You don't need to dump heat from the storage tank necessarily.

 

[all night moe]

So in the event of a power outage, the thing that would overheat is the furnace. That's where the fire is. So if you can get a vertical rise directly from the furnace coil to the heat dump, that would work. You don't need to dump heat from the storage tank necessarily.

Power or not, my furnace can overheat the water. It is not controlled by a thermostat. Wood is the only heat source, and it's using this furnace. Intake air is controlled manually. When I leave for work, 6-8hrs, I leave the intake damper open about a 1/4''. This will net me a nice bed of coals, upon my return. Firebox is 24x24x48. I don't fill it, but throw in a decent load of splits before leaving. If the water gets to hot, I'd prefer to dump the heat in the crawl space. There isn't much space available above the furnace. Low 1800s basement ceiling and tons of crappy antique duct work.

 

[all night moe]

Using an aquastat, which one would I want to open the zone valve? The ones I am finding are open contacts at high temp.

 

[gthomas785]

If your zone valve is normally closed, you'd want a Low limit aquastat.

 

[gthomas785]

Sorry to be more specific it needs to be "close on rise". They do exist but most are the other way because usually you are trying to turn on a heating device, not dump the heat.

Here's one there can be wired as either close on rise or open on rise. It's a strap on but they make the probe type as well

https://www.supplyhouse.com/Resideo-L6006C1018-High-or-Low-Limit-Circulator-Strap-On-Aquastat-65-200-DegreeF-range-5-30-DegreeF-Adj-Differential

 

[all night moe]

@gthomas785 thank you for all of your help.

 

[brenndatomu]

Using an aquastat, which one would I want to open the zone valve? The ones I am finding are open contacts at high temp.

So wire that to a DPDT relay and use the NO contacts to control the dump...

 

[all night moe]

So wire that to a DPDT relay and use the NO contacts to control the dump...

DPDT?

 

[brenndatomu]

DPDT?

Dual pole dual terminal...in other words, 2 sets of NO/NC contacts

 

[pettibone]

Why not just run it to the kitchen with a circulator and none of the other stuff and see if it even makes enough heat to make a big system? My stove was disappointing but it made steam with no power.