Adding water exchanger to VC Defiant

[Wyld-Bill]

I have posted on here in the past but I couldn't remeber my password. I think My screen name was Wyld Bill or Wyld_Bill.

Anyways, I am adding a water coil to my VC Defiant stove.
It is going to be piped into my solar hot water system. I am also adding a second tank to my domestic hot water system.

 

[Wyld-Bill]

I have posted on here in the past but I couldn't remeber my password. I think My screen name was Wyld Bill or Wyld_Bill.

So anyways I am adding a water coil to my VC Defiant stove.
It is going to be piped into my solar hot water system. I am also adding a second tank to my domestic got water system.

Here is my piping design layout.

 

[Heftiger]

That looks very complex, and intriguing!

 

[Starstuff]

Interesting! Please keep us updated.

 

[Wyld-Bill]

Interesting! Please keep us updated.

I will
I've been super busy at work so haven't done much on it. I need to get the exchanger filled though because the copper is getting so hot that most of it is now dark brown in color.

 

[jharkin]

One thought - You put the water coil against the right side panel with the thermostat. The thermostat handle is attached to a bimetallic coil just inside that panel, the additional heat absorption of the water coil is going to cool the thermostat and make it open the air inlet more than expected (stove may run hot).

You might get better results attaching the coil to the back panel to take the heat directly radiating off the catalyst chamber. That's typically the hottest part of a VC stove by far. Danger is there is a greater chance of boiling your water line if you are not careful.

Which brings me to the usual safety caveat: Understand that unlike your gas/oil/etc fired boiler there are no automatic controls on the woodstove that will shut the fire down if the water temp gets out of control. You must design in some method to prevent the water flashing to steam in those lines, and safety valves to give the pressure somewhere to go if it does so anyway (due to power outage, pump failure, pipe blockage, stove runaway, etc).

 

[Wyld-Bill]

One thought - You put the water coil against the right side panel with the thermostat. The thermostat handle is attached to a bimetallic coil just inside that panel, the additional heat absorption of the water coil is going to cool the thermostat and make it open the air inlet more than expected (stove may run hot).

You might get better results attaching the coil to the back panel to take the heat directly radiating off the catalyst chamber. That's typically the hottest part of a VC stove by far. Danger is there is a greater chance of boiling your water line if you are not careful.

Which brings me to the usual safety caveat: Understand that unlike your gas/oil/etc fired boiler there are no automatic controls on the woodstove that will shut the fire down if the water temp gets out of control. You must design in some method to prevent the water flashing to steam in those lines, and safety valves to give the pressure somewhere to go if it does so anyway (due to power outage, pump failure, pipe blockage, stove runaway, etc).

All good points and I appreciate the advice.

Just so you I am a heating technician with 20+ years experience, well not a heating tech anymore, now I am service manager for an HVAC company with 45 employees.

I will show how it all works as I go along.

I was going to put the coil on the rear of the stove (it actually would have been easier) but this is a NC so the rear of the stove actually stays realitively cool, it is where the air for combustion comes in as far as I can tell.

 

[Wyld-Bill]

Progress photos. All of the piping in my den/man cave is done.

Outlet fluid temperature.
When the temperature of the Woodstove sensor is 20 degrees hotter than the temp of my 80 gallon indirect solar tank my circulator pump will start and run to maintain 5 degrees diff between the fluid out of the Woodstove coil and the fluid coming from the solar tank. I will not allow the pump to run unless the coil outlet temp is over 150 degrees. This will keep the coil from robbing too much heat from the wood stove which could affect the operation of the Wood stove and cause me to not get enough heat to heat my house.
This is the coil outlet sensor below.

 

[Wyld-Bill]

You can see the heat gradient by the coloration on the copper coil. The top I would say at some point got over 600 degrees F.

I didn't remeber this particular stove having a thermostat persae but instead a manual air damper control. I used to have an 80s VC Encore that had the true thermostat control.
It's funny in the book they call it the "primary air Thermostat handle" but in the exploded parts diagram I see nothing that looks like a coiled up thermostat device. I think it may be a misprint from the older models that had a true thermostat.

Here is my 80 gallon solar tank (indirect with a coil on top and a separate coil on bottom) that I bought new/used for $500.
My controller, domestic and solar loop expansion tanks, heating zones, etc.



Caleffi MX LTE solar/whatever controller and data logger (same as a Resol iSolar BX)
9 inputs for temperature, 2 Grundfos direct sensor inputs, one irradiation sensor input, 4 powered output relays, 2 PWM outputs, and 1 dry set of contacts. Can be connected to the Internet via Vbus.

 

[pdxdave]

Very cool !
Couple questions - what is the Hydro Coil for up top ? Is that for heat rejection or something else ? How is flow controlled to it ?
Do you have a 'sequence of operation' and what are you using to control the motorized valves ? I'd definitely like to hear a bit more about how it works.

 

[pdxdave]

Progress photos. All of the piping in my den/man cave is done.

Outlet fluid temperature.
When the temperature of the Woodstove sensor is 20 degrees hotter than the temp of my 80 gallon indirect solar tank my circulator pump will start and run to maintain 5 degrees diff between the fluid out of the Woodstove coil and the fluid coming from the solar tank. I will not allow the pump to run unless the coil outlet temp is over 150 degrees. This will keep the coil from robbing too much heat from the wood stove which could affect the operation of the Wood stove and cause me to not get enough heat to hear my house.
This is the coil outlet sensor below.

Ahh, nice. So - how will you know the coil outlet is operating above 150 - won't you need to have flow through it to read the temp ? Maybe a contact sensor up higher on the coil would give a better reading for initiating the pump ? Is the pump variable speed?

 

[Wyld-Bill]

Very cool !
Couple questions - what is the Hydro Coil for up top ? Is that for heat rejection or something else ? How is flow controlled to it ?
Do you have a 'sequence of operation' and what are you using to control the motorized valves ? I'd definitely like to hear a bit more about how it works.

Hydro coil up top is a large deep copper with aluminum finned coil I have in my attic up near the peak. It is not done yet but my thought was to reclaim heat from the attic during the summer months. This would help cool my attic and heat the dom water. I was going to use some Harbor Frieght solar panels to power two automotive radiator fans that would move the hot air through the coil. The sunnier it gets out the faster they run. I'd have the solar panels hooked to a deep cycle battery. After the sun went down the fan would still run for awhile until the battery(s) die.
I will be typing up a sequence of operation once I have played with it and finalized everything.
Right now the SO-Op is in my head.

 

[Wyld-Bill]

Hydro coil up top is a large deep copper with aluminum finned coil I have in my attic up near the peak. It is not done yet but my thought was to reclaim heat from the attic during the summer months. This would help cool my attic and heat the dom water. I was going to use some Harbor Frieght solar panels to power two automotive radiator fans that would move the hot air through the coil.
I will be typing up a sequence of operation once I have played with it and finalized everything.
Right now the SO-Op is in my head.

And yes this coil could also be used for heat rejection,...especially in the winter if for some reason the Woodstove heating coil loop got too hot.

 

[Wyld-Bill]

Ahh, nice. So - how will you know the coil outlet is operating above 150 - won't you need to have flow through it to read the temp ? Maybe a contact sensor up higher on the coil would give a better reading for initiating the pump ? Is the pump variable speed?

The outlet is very near the actual coil on the stove so the two should be similar BUT Of course as the pump starts to run the temp may go up some then it will drop depending on the speed of the pump at that point but it should be fine, actually that's what you want. That way the pump speed can modulate as it needs to.
If that doesn't pan out I have a sensor on the actual Woodstove that I can add into the mix also.
So yes, the pumps are variable speed.

 

[pdxdave]

The outlet is very near the actual coil on the stove so the two should be similar BUT Of course as the pump starts to run the temp may go up some then it will drop depending on the speed of the pump at that point but it should be fine, actually that's what you want. That way the pump speed can modulate as it needs to.
If that doesn't pan out I have a sensor on the actual Woodstove that I can add into the mix also.
So yes, the pumps are variable speed.

Makes sense, having the vfd pumps goes a long way in this type of setup. I've seen solar setup with const volume pumps and it is always a mess control wise. What are you using for the control system ? I'm in the DDC industry so interested to hear about it ! - Edit Nevermind just saw your post above.

 

[Wyld-Bill]

My wood stove set up.

I bought it for $400.
Someone before me bought it, and thought it needed to be rebuilt after they used it a couple months. They took it apart, broke some pieces, and didn't know how to put Humpty Dumpty back together again.
A buddy and I had to go get it and all the pieces.
I spent around $400. After I bought it Rebuilding it. That was three years ago. I've put about 10 cord of wood through it since I got it.
Yes I have trouble with it back puffing. My wife and I have learned how to limit or virtually eliminate the back puffing issue.

The hood over the stove catches the hot air and directs it up through a large cast iron floor grate in the center of the house. The house a single level ranch with passive solar gain from large windows on the south side. The house has a daylight finished basement which is where the Woodstove, boiler, and solar tank is.

I am collecting data of the hot air temp off the wood stove going through the floor grate and also the actual Woodstove temp every 4 minutes and storing it on an SD card in my solar controller.

 

[Wyld-Bill]

Makes sense, having the vfd pumps goes a long way in this type of setup. I've seen solar setup with const volume pumps and it is always a mess control wise. What are you using for the control system ? I'm in the DDC industry so interested to hear about it ! - Edit Nevermind just saw your post above.

Yeah it's basically a "wave chopper" control.
I wish we had the ECM motors available in the states. The controller I have will run two ECM motors,....if you have them.

 

[Wyld-Bill]

These are two thermal disk temp switches. One closes if the flue pipe gets too hot (Woodstove overheating) the other closes of the temp of the flue pipe gets below 150 degrees (fire is going out)
They trigger a annoying buzzer that can only be stopped by fixing the problem or shutting off a switch beside the wood stove.
When this buzzer goes off in the middle of the night I SPRING out of bed and RUN downstairs. 1. Because something may be wrong with the wood stove.
2. If the loud buzzer wakes up my wife she'll kill me.

 

[Wyld-Bill]

Taco SR506 EXP zone pump relay controller. Priority for domestic (not that I really need it),
6 pump control (currently running 4 zone pumps) with a boiler reset control PC700 (Tekmar)
Above those is a Taco ZVC404 zone valve controller. It is controlling my three basement zones.

 

[Wyld-Bill]

The more views and comment I get,..the more pictures and description I will add.

If no one is interested then I am going to stop posting on the thread because it is time consuming.
;-)

 

[twd000]

I'm defiantly interested and appreciate your description. Still trying to figure out how the controls work. As for myself, I have a Woodstove in the basement That needs to run hot to keep the catalyst active. Since the basement is small this overheats that room. I was pondering adding a water jacket to bleed off some of that excess heat and put it to good use. Since space heating requires more BTUs than water heating, what about running a PEX line upstairs and installing some hydronic Zones under the floors?

 

[Wyld-Bill]

I'm defiantly interested and appreciate your description. Still trying to figure out how the controls work. As for myself, I have a Woodstove in the basement That needs to run hot to keep the catalyst active. Since the basement is small this overheats that room. I was pondering adding a water jacket to bleed off some of that excess heat and put it to good use. Since space heating requires more BTUs than water heating, what about running a PEX line upstairs and installing some hydronic Zones under the floors?

You can see the heat gradient by the coloration on the copper coil. The top I would say at some point got over 600 degrees F.

I didn't remeber this particular stove having a thermostat persae but instead a manual air damper control. I used to have an 80s VC Encore that had the true thermostat control.
It's funny in the book they call it the "primary air Thermostat handle" but in the exploded parts diagram I see nothing that looks like a coiled up thermostat device. I think it may be a misprint from the older models that had a true thermostat.

Here is my 80 gallon solar tank (indirect with a coil on top and a separate coil on bottom) that I bought new/used for $500.
My controller, domestic and solar loop expansion tanks, heating zones, etc.

View attachment 169187

Caleffi MX LTE solar/whatever controller and data logger (same as a Resol iSolar BX)
9 inputs for temperature, 2 Grundfos direct sensor inputs, one irradiation sensor input, 4 powered output relays, 2 PWM outputs, and 1 dry set of contacts. Can be connected to the Internet via Vbus.

View attachment 169188

I put a video of my set up on you tube.

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