Kumma VF100 install with a Electric Plenum Heater

[BuckHunt]

Hello all,

I recently purchased a VF100 and will be using it as my primary heat source in my house. I currently have a LP furnace with an electric Plenum heater installed that can be used as backup or main heat source. This past winter I used only the electric heater and it worked fine to keep the house heated.

So moving on I want to remove the LP furnace and replace it with the VF, while keeping the electric plenum heater as back up for if we leave for an extended amount of time.

So I was wondering if anyone else had done this? I have been doing some looking about installing the heater and one of the things that worries me this that I've read that with some the furnace can't be putting out more than 180 degree into the plenum. I'm thinking the VF will probably be doing more than that. I know I can adjust the high limit down to that, but in the event of a power outage and the furnace is gravity feeding I think the temperature will exceed that.

Any insight would be appreciated!

Ben

 

[Smoke Signals]

I'm not sure but I think the heat strips would be ok but where you will have a problem is if you have an "A" coil mounted in the plenum for cooling, the heat from the furnace will damage it.

 

[STIHLY DAN]

Hard to read what you posted, but if you wired w2 on T-stat to fan on Kuuma and electric heat you have no issues.

 

[BuckHunt]

The A coil can come out, mainly worried that the plenum heater might get damaged from the heat of the furnace if the power goes out and the furnace is still running. From reading the manual it sounds like it gets hot when the fan isn't blowing!

 

[brenndatomu]

A heater that can be damaged by heat?! That doesn't sound right to me. As SS said, maybe the A coil, but I would think the electric heater coils would surely be OK?! My Yukon is certified to be able to run during power failure and they claim that it is fine to leave the A coil in year round as long as you replace the plastic drip tray with a metal one, I didn't wanna take a chance on it so designed the plenum so that the coil can be pulled in the winter, anyways...
If you are concerned about it though, you can install a heat dump for power failures...two ways (at least)
1. Put a large power close/spring open damper on the plenum to open up and dump some heat to the basement when power goes off
2. A fusible link activated heat dump door like the one Yukon sells http://www.yukon-eagle.com/FURNACEACCESSORIES/SAFETYHEATDUMP/tabid/200/Default.aspx

 

[BuckHunt]

A heater that can be damaged by heat?! That doesn't sound right to me. As SS said, maybe the A coil, but I would think the electric heater coils would surely be OK?! My Yukon is certified to be able to run during power failure and they claim that it is fine to leave the A coil in year round as long as you replace the plastic drip tray with a metal one, I didn't wanna take a chance on it so designed the plenum so that the coil can be pulled in the winter, anyways...
If you are concerned about it though, you can install a heat dump for power failures...two ways (at least)
1. Put a large power close/spring open damper on the plenum to open up and dump some heat to the basement when power goes off
2. A fusible link activated heat dump door like the one Yukon sells http://www.yukon-eagle.com/FURNACEACCESSORIES/SAFETYHEATDUMP/tabid/200/Default.aspx

That was my thinking. I just read on one plenum heater manual that stated the temp couldn't get above 180 degrees. I couldn't find anything about that for my model plenum heater, just wondering if anyone else had run into that.

Now you have my attention. I was thing that if I could get it so I could just remove the A coil during the heating season I wouldn't have to worry about it. How did you go about being able to remove it?

 

[brenndatomu]

Now you have my attention. I was thing that if I could get it so I could just remove the A coil during the heating season I wouldn't have to worry about it. How did you go about being able to remove it?

I left the line set long and routed it with a large S shape to it so that I can carefully flex the lines and slide the coil just outside the plenum through the removable side panel, then I sit the coil on a homemade "shelf" that hangs from the floor joist above during the winter. By very carefully flexing the lines over a 10' to 15' long S shaped length it allows movement of the coil while leaving the system charged and not causing any damage. My plenum was custom made right from the get-go to be able to do this, pretty simple really.

 

[Smoke Signals]

Do you have room to leave the gas furnace as is with the heat strips and "A" coil and use it for cooling and back up electric and install the Kuuma next to it with it's own plenum?

 

[BuckHunt]

Do you have room to leave the gas furnace as is with the heat strips and "A" coil and use it for cooling and back up electric and install the Kuuma next to it with it's own plenum?

I thought about doing this, and it would be simpler. However I would be tight on space and would have more difficulty connecting the Kumma to my cold air return duct, plus would not be able to use the domestic hot water coil the Kumma.

 

[BuckHunt]

I left the line set long and routed it with a large S shape to it so that I can carefully flex the lines and slide the coil just outside the plenum through the removable side panel, then I sit the coil on a homemade "shelf" that hangs from the floor joist above during the winter. By very carefully flexing the lines over a 10' to 15' long S shaped length it allows movement of the coil while leaving the system charged and not causing any damage. My plenum was custom made right from the get-go to be able to do this, pretty simple really.

Interesting. Where did you have your plenum made?

 

[brenndatomu]

Interesting. Where did you have your plenum made?

I did some bartering for labor with my neighbor who works for a local HVAC shop, he is their tin knocker
I had originally gotten a quote from another shop, they didn't seem too keen on doing the job...quoted me $1000 to do what I wanted! I wasn't expecting that...

 

[BuckHunt]

I did some bartering for labor with my neighbor who works for a local HVAC shop, he is their tin knocker
I had originally gotten a quote from another shop, they didn't seem too keen on doing the job...quoted me $1000 to do what I wanted! I wasn't expecting that...

Dang! My wife keeps telling me just to have someone come and do it for me, but I am trying to avoid a bill like that haha. I wanted to try just using a plenum from Menards, but I'm still trying to work out it's all going to work.

 

[brenndatomu]

Well, my situation probably is not a good example of what you should expect ductwork to cost. I was trying to re-use as much of the original ductwork as I could, and I have a pretty complicated system, a lot going on in a small space, 10#s of duct in a 5# box so to speak. Chances are you can use off the shelf parts...

 

[STIHLY DAN]

I left the line set long and routed it with a large S shape to it so that I can carefully flex the lines and slide the coil just outside the plenum through the removable side panel, then I sit the coil on a homemade "shelf" that hangs from the floor joist above during the winter. By very carefully flexing the lines over a 10' to 15' long S shaped length it allows movement of the coil while leaving the system charged and not causing any damage. My plenum was custom made right from the get-go to be able to do this, pretty simple really.

Or just remove the plastic condensate pan and install a metal one. many units still use metal pans.