Tarm Plumbing Design Question

[DenaliChuck]

Can someone help me figure out the operation of the system that BioheatUSA has designed?

I cannot tell how the system would prioritize providing heat to the house from the wood boiler first (if hot), then the storage tanks (if hot), then the fossil boiler.

Thank for your insight!

DC

 

[BrownianHeatingTech]

The little green box on the left, at the top, controls the switch-over between the tanks and the fossil fuel backup.

The loading unit pumps water from the Tarm to the piping that leads to the tanks and the rest of the system. When no zones are calling, C-1 is off, and the water goes through the tanks. When a zone calls, the C-1 is activated, and it will draw water away from the Tarm/tank assembly. The diverter valve (to the left of C-1) controls how much water C-1 draws, based upon the thermal draw of the zone.

Joe

 

[DenaliChuck]

Thanks Joe.

But when the C-1 is off, what moves the water through the tanks? Is there a circulator I'm not seeing?

 

[BrownianHeatingTech]

Thanks Joe.

But when the C-1 is off, what moves the water through the tanks? Is there a circulator I'm not seeing?

C-3, which is part of the loading unit.

Joe

 

[DenaliChuck]

Thanks Joe, that C-3 almost bit me.

I'll be using a flat plate hx to the right of C-1 to isolate my Tarm/Storage side from the existing house system.

Since I'll be providing the hottest water from the Tarm/Storage side to the primary loop side of my existing system, I shouldn't need the Termovar diverter valve "G" right?

 

[BrownianHeatingTech]

Thanks Joe, that C-3 almost bit me.

'Tis why we don't include rattlesnakes in diagrams - we'd all be dead, eventually!

I'll be using a flat plate hx to the right of C-1 to isolate my Tarm/Storage side from the existing house system.

Since I'll be providing the hottest water from the Tarm/Storage side to the primary loop side of my existing system, I shouldn't need the Termovar diverter valve "G" right?

The diverter blends the water based upon the load. Without it, any time that any zone called, all the heat would try to go to the zone, and none would go to the tanks. If it were a large zone that could absorb the boiler's full output, that would not be an issue. If it's a small zone (or a large zone, on a warm day), the boiler would hit high limit and shut down, thereby defeating the purpose of having the tanks. You can do the same with an electronic mixing control, but some form of mixing should be used.

Joe

 

[chuck172]

For the life of me, I just don't understand how the diverter valve blends the water based upon the load in the above tarm drawing.
Can you go into some more detail on this Joe?
Anyone else is also welcome to try to get this through my thick skull.

 

[DenaliChuck]

This is applicable only when the boiler is running and the house calls for heat.

If the return water from the house is cold (high load) then the diverter valve G will circulate the returned water back to the boiler to be heated and the tank will receive nothing. If the house return water is warm (low load) then valve G will add some of the the warm house return water to the hot wood boiler supply water and send it back to the house.

As an example, if the valve G adds 25% of the house return water to the boiler hot supply water (because the house load is small), that would allow 25% of the boiler hot supply water to be circulated through the storage tanks at the same time the house needs are being met. It allows simultaneously supplying the house what it needs, and the leftover would supply the tanks.

Clear as mud?

As an aside, I'm FINALLY getting to the plumbing of my system The addition construction project is far enough along that copper can be installed!

 

[chuck172]

Thanks DenaliChuck, I spoke with Chris from BioHeat and he's helping me on this too. I think I'm starting to understand it and I might re-pipe my system this spring.
By the way, you say you're about ready to start the piping, Have you ever heard the song "When it's springtime in Alaska, its forty below" by Johny Horton.

 

[DenaliChuck]

I haven't heard the song, but hope it doesn't describe this spring...at least until the boiler is plumbed!

 

[BrownianHeatingTech]

I was going to reply, but I guess I missed my chance!

Joe

 

[chuck172]

Thanks anyway Joe, I think I got it now.

 

[flyingcow]

I know you got it figured out now, but just for your info, just had my system installed with all the termovar valves, BLT controls, loading valves, etc per Tarms' diagrams, and specs. Works very well.

 

[hoth2oguy]

thanks Denali and Joe, excellent explanations, couldn't have said it better myself.....no, really!

 

[DenaliChuck]

To place credit where it is due...I developed my understanding from Joe!

Thanks for the thumbs up on system design flyingcow, I can't wait to see (feel) mine work!

Chris, I got my system prior to the all in one loading valve. The Termovar you guys provided, coupled with the circ I purchased have should work just like the new loading valve, correct?

DC

 

[hoth2oguy]

yes DC, Termovar and circ pump will work just fine.

 

[hoth2oguy]

DC, be sure you include a ball valve just above port one of the Termovar. This ball valve should be set at about half way closed - unless you are an optimist, then is should be set half way open......sorry, haven't had my first cup of coffee yet!