Garn Install help / diagram

[jas702]

I am in the process of installing a new (to me) Garn 2000 in a remote building about 150ft from my house.

I need help with the plumbing and electrical diagrams. I was in touch with Chris Holley and he did the heat load calculations, and recommended depressurizing my current system because the height of the Garn is about midway between the lower and upper level of my house. I asked Chris to help with the system design (for a fee of course) but its been a bit of radio silence since September.

I understand the basics but I want to spend the time and money of having a proper design so I am not re-plumbing or buying fittings, pumps, etc twice.

Background:
Garn is 2009, I purchased the digital controller, gaskets set, chemicals, had my water tested, Logstor 1.25 insulated underground Pex installed between house and barn. Stainless class A chimney installed vertical inside the barn, intake air damper, etc all per Garn manual.

I have an oil fired boiler with 3 zones, 1 zone is indirect fired Hot water tank. other 2 zones are HWBB for upper and lower level. Chris also recommended moving the two ciculators for HWBB to supply side. I have a little more baseboard then required for my heat load and should be able to use storage temp down to 135.


What controls are used for the Oil Burner in the event that the storage temp on the Garn is too low?

Does anyone run their system depressurized?
Do you have plumbing schematics and electrical schematics?


Thank you.

 

[mike van]

jas - into my 6th year with a Garn, this year I took a shot at running without a HX, or 0 pressure on the house side. Worked for almost a week, then one night I lost the second story loop, air in it, could not get it out. Finally went back to the HX as cold weather was coming. Works as flawless now as it did before. The circulators in my basement are set up to suck cold water down, I think if they pushed hot water up or had their flow reversed, it would have worked fine. I just didn't have the time right then to cut it all apart. I may revisit someday.

 

[TCaldwell]

Hi joe,
I wouldn’t give up on Chris yet, he’s been busy as it’s the season, maybe send him some pics as to where you are at. I’m not sure you will get much unpressurized help from anyone else as it’s sort of uncharted territory.
I’m running that way, however still have a couple ghosts I’m trying to understand in the mixing behind the garn.
I will say with the approach temp of the flat plate out of the equation, it’s pretty much direct drive, and can run storage down another 7 degree per burn. Water was tested and added chemicals, should be good in that department for a while.

 

[jas702]

Mike- thank you, do you have a backup boiler? Do you know what controllers are used for both boilers?

Tom- Thank you, I haven't given up. Chris has been more than helpful so far, I didn't think I would get it all hooked up before the heating season, since I didn't get the boiler home until Sept. 24, My goal was to get the underground lines in and insulate the barn before the winter but that was finished up quicker than expected.

 

[TCaldwell]

Joe, once you know how you want the system to work, that will dictate the control options. Are you piping the garn and backup in series or parallel, how is the domestic hw handled, do you want to use outdoor reset, what type of emitters, mixed zone temps or single temp. Once these are determined then appropriate Controlls can be selected.
I believe mikes garn is tied in to his Oiler with a set of closely spaced t’s, keeping his Oiler hot as that supplies his dwh, thus piped in series. The Oiler aquastat lower limit setting becomes the toggle temp between boilers and the garn circ.

 

[jas702]

Tom- DHW with existing indirect tank. I was going to pipe the boilers in parallel. Oiler only coming on if Garn is below temp, but connected in a way that i would not heat the storage with oil. Chris sent me these two generic diagrams when I had first contacted him. Based on that diagram I am adding a circulator to the oiler, because my current system has a circulator for each zone. The other circulator will be in the barn with the Garn. I am also going to reverse the flow in my existing system because the two HWBB circuits have the pumps on the return. He said I should get a Tekmar 256 and mount it in a convenient spot in the house to monitor the Garn temp. No outdoor reset, because of the higher supply temps for DHW. Single zone temps, all baseboard for the two zones. I will use a fan coil in barn, but that will be down the road, I want to see how much heat I get from just having the boiler in the barn and well insulated/enclosed from the rest of the space. If the DHW or lack there of becomes an issue, I may look into an on demand propane water heater.

 

[TCaldwell]

Hi joe,
With this diagram, parallel plumbed you won’t heat storage with the oil boiler, if that’s your concern. This is basically how my system is plumbed, garn on one set of closely spaced t’s and the Oiler on the other, zone circs on the supplies.
The wiring diagram looks easy to follow, the ranco toggles between the boilers

 

[mike van]

Mike- thank you, do you have a backup boiler? Do you know what controllers are used for both boilers?

My Garn is plumbed through the old 1963 boiler in the basement. The house was a one story ranch about 1200 sf as built. Many changes & additions later, sometimes I think i'd be better served to cut it all apart & repipe it. Of course, right after I did, the old boiler would probably fail. Someday I need a generator, if theres a power outage, we'd have no heat. Almost none, I'd be most worried about the pipes from the garage addition where the Garn is to the house. Our dhw comes off the old boiler, but the Garn heats it. The Garn has the controller they provide with it, I did add a timer to the blower side though, as I thought it ran way too long after the fire was gone. About an hour 45 minutes is plenty for a good load of hardwood, the factory setup was well over 2 hours every load. The kwh up fast with the 1/2 hp blower running. The control on the oil boiler is the same as on any, I just turn the on setting way down so it's not kicking on at all. I run the Garn down to 128 before the aquastat trips it off.

 

[jas702]

Mike- thank you

Tom- Thanks again, I can start with that while I am waiting to hear back from Chris.

 

[TCaldwell]

Hi joe,
Did Chris send you the detail for the common piping header with the closely spaced t’s? If not let me know the underground pex id and I can make you a diagram.

 

[jas702]

Hi Tom,

Thanks for the diagram.

Hi joe,
Did Chris send you the detail for the common piping header with the closely spaced t’s? If not let me know the underground pex id and I can make you a diagram.