Insulating Garn Manway

[Sugarmaple]

The Garn manual says that it's not necessary to insulate the manway because there isn't much heat loss. It seems to m that there is a significant amount of heat loss there. I've tried a couple of methods of inssulation while staying within the constraint of not getting a tight seal on the cover. The problem is I'm getting a lot of condensation. What do you Garn owners do?

 

[Rick Stanley]

I haven't insulated my manway. I have, however, been cautioned about making sure that the foam gasket on the underside of the cover make a good tight seal because if it doesn't, it can cause condensation which will soak the insulation and cause a mess.
So, maybe the reason that it seems you have a lot of heat loss is the same reason you have a lot of condensation. Maybe the gasket is leaking. Just a thought.........

 

[Sugarmaple]

I don't think so, there's no condensation without insulation. I'll check it, though. My "there's a lot of heat loss" observation is a subjective one, I haven't attempted to measure it. I just hate seeing that heat dissipate into a cold drafty barn.

 

[TCaldwell]

sugarmaple, rick is right about the manway gasket and condensation, understanding that is not what you are refering to, but i took a 5/8 inch foam backer rod , ran a slit along a length needed to slip over the boiler riser lip and set the manway lid ontop of the new backerrod gasket, fits snug and no condensation on the boiler insulation. i suppose that you could cover the manway cavity with foam board

 

[Sugarmaple]

Well, I was just fiddling around with it trying to make adjustments. I don't see how you can not have condensation given the conditions. The water temp is 190 F, which means the the cover is 190 F, and the air temp is 35 F. It's like putting a tightly covered pot of boiling water in the refer. I tried pushing down on the cover and it didn't seem to reduce the amount of "steam".

I tried the foam board, but I didn't get a real tight seal. It was ugly.

 

[RowCropRenegade]

Funny this was posted today. Cut out manway today. Made it a little bigger than needs to be, just in case.

Sugarmaple, can you box up manway access hole (not garn manway hole) and create a seal? Or some kind of vent? That was my plan until this thread popped up.

 

[Jim K in PA]

Where is the condensation forming? It sounds like you have a significant humidity level in the air above the GARN. If you have a proper, complete seal between the lid and the manway of the GARN tank, then you should have no moisture loss from the tank to cause condensation. Reducing the amount of open space around and above the manway should help reduce condensation levels.

BTW - did you plug the return bung on the manway collar?

 

[Rick Stanley]

Yup, my garn is in an unheated building also. The only time I see steam anywhere is a few times I lifted the manway lid and it puffs out bigtime. Drop it back in place and it stops.

 

[Sugarmaple]

Yeah, that bung is plugged. I only got condensation when I tried to insulate and cover the manway. There's plenty of space above the manway, probably 15 feet. When it's open, it's okay. There's plenty of space above the manway, probably 15 feet. I played with it this morning and got it so there's an almost imperceptible trickle of steam wafting about.

 

[heaterman]

The lid on the manway is concave to allow any condensation formed on the underside to drop back into the tank. Any leakage from the lid is most likely due to misaligned or crushed gasket. I just place a piece of 2" blueboard on top of the lid to minimize what little heat loss there is from that area.