Insulating the manhole on a Garn

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Sawyer

Sawyer

Minister of Fire
May 17, 2008
608
Northern WI
How have you insulated the manhole on your Garn?

I have the insulation below the rafters complete as of last night except for the manhole opening. I can feel vapor moving upward around the manhole cover and am worried that fiberglass may become saturated and become ineffective.

I believe I read at one time that someone had applied weight to the cover to stop this problem but do not remember if that solution worked.
 
I don't think it is a good idea to put weight on the cover.It is meant to rise in case of a boil over
 
Do a light dusting of www.tigerfoam.ca you can buy a small spray foam kit, same as what the spray guys have in there trailers. Tape off the lid as you would when you would paint and give it a inch or so that would be around R6. I imagine you can find other areas in your house to use the kit up in or just do the whole top of the tank in a thin layer, then put your battens around this. You've gone this far already, may as well get the boiler sealed up.
 
My Garn rep told me to check the flatness of the manhole. He said there may be a weld holding it up or it may have a high spot that could be ground down slightly. I will check tomorrow.

I like the idea of foam. I have a can of Great Stuff and plan to foam the cover only, taping off the access to the low water sensor in case access is needed later to service the device. With closed cell foam, moisture would not be an issue.
 
I'm looking at the GARN at the moment for my heating needs, very early stage of development. But my thoughts or to use the spray kits to coat the holding tank especially the top and lid, if I were to purchased one of these units. A one inch thick coat over the whole tank of the unit, excluding the front would offer a huge savings in btu's savings in years to come. The kits allow you to do it yourself. I think it would be worth the extra $ to have the unit sprayed foamed. I'm little spray foam pro active. Everything I build seems to get sprayed sooner or later. I'm surprised to that GARN does not sell them all sprayed up.

Sawyer I've been reading and watching your posts, making me want to take the GARN route. Very expensive but at the same time the savings and simplicity would be worth the effort, in years to come.
 
Extremebison said:
I'm looking at the GARN at the moment for my heating needs, very early stage of development. But my thoughts or to use the spray kits to coat the holding tank especially the top and lid, if I were to purchased one of these units. A one inch thick coat over the whole tank of the unit, excluding the front would offer a huge savings in btu's savings in years to come. The kits allow you to do it yourself. I think it would be worth the extra $ to have the unit sprayed foamed. I'm little spray foam pro active. Everything I build seems to get sprayed sooner or later. I'm surprised to that GARN does not sell them all sprayed up.

Sawyer I've been reading and watching your posts, making me want to take the GARN route. Very expensive but at the same time the savings and simplicity would be worth the effort, in years to come.
Click to expand...

Garn specifically stated when i bought mine that it should not be foamed nor should cellulose be used. I think it had to do with a reaction to the metal. The manhole cover is aluminum so it would be ok.
 
Sawyer said:
Extremebison said:
I'm looking at the GARN at the moment for my heating needs, very early stage of development. But my thoughts or to use the spray kits to coat the holding tank especially the top and lid, if I were to purchased one of these units. A one inch thick coat over the whole tank of the unit, excluding the front would offer a huge savings in btu's savings in years to come. The kits allow you to do it yourself. I think it would be worth the extra $ to have the unit sprayed foamed. I'm little spray foam pro active. Everything I build seems to get sprayed sooner or later. I'm surprised to that GARN does not sell them all sprayed up.

Sawyer I've been reading and watching your posts, making me want to take the GARN route. Very expensive but at the same time the savings and simplicity would be worth the effort, in years to come.
Click to expand...

Garn specifically stated when i bought mine that it should not be foamed nor should cellulose be used. I think it had to do with a reaction to the metal. The manhole cover is aluminum so it would be ok.
Click to expand...

Hay great info, I haven't had the chance to ask my rep yet about this.

Byron
 
I would be curious as to why the garn should not be closed cell foamed, it is basically a hw storage tank. If e 84 fire retardant foam was used on areas only exposed to 250degf or below temps?
 
Would love to see the lid pics when your done, curious to see how it all works out for yah
 
Sawyer said:
How have you insulated the manhole on your Garn?

I have the insulation below the rafters complete as of last night except for the manhole opening. I can feel vapor moving upward around the manhole cover and am worried that fiberglass may become saturated and become ineffective.

I believe I read at one time that someone had applied weight to the cover to stop this problem but do not remember if that solution worked.
Click to expand...


The manhole on mine was not seating properly against the gasket , allowing vapor to escape. I ran my fingers around the cover to center it and that done the trick.

I had plywood over my insulated joist on top of the boiler. I made a trap door out of pylwood and attached 11/2" styrofoam to the under side.

Hope this helps..good luck.
 
TCaldwell said:
I would be curious as to why the garn should not be closed cell foamed, it is basically a hw storage tank. If e 84 fire retardant foam was used on areas only exposed to 250degf or below temps?
Click to expand...

I will ask my rep the next time we talk. I believe it was a reaction to the fire retardant in the cellulose that was the problem. Perhaps it is the same with the foam?
 
Yes, that is correct George. According to Dectra, the fire retardent will interact with the tank. I think Garn is just uncertain what the long term effects of foam might be, again corrosion concerns, so they clearly state don't do it (spray it).

I've been planning to fabricate a cyclinder (semi-rigid plastic sheeting perhaps?) to place around the manhole cover to extend up and outside the Garn box. I haven't noticed any vapor leaks, but I haven't been really looking much up there. When I took my water sample a few weeks ago, there was no lack of vapor! So having a dedicated exit for whatever steam may exit sounds like a good idea.

Dectra is explicit about not weighting down the lid. Presumably steam will exit the boilover port if it starts to boil....but it seems allowing the lid to lift would be a good thing.
 
nt30410 said:
Sawyer said:
How have you insulated the manhole on your Garn?

I have the insulation below the rafters complete as of last night except for the manhole opening. I can feel vapor moving upward around the manhole cover and am worried that fiberglass may become saturated and become ineffective.

I believe I read at one time that someone had applied weight to the cover to stop this problem but do not remember if that solution worked.
Click to expand...


The manhole on mine was not seating properly against the gasket , allowing vapor to escape. I ran my fingers around the cover to center it and that done the trick.

I had plywood over my insulated joist on top of the boiler. I made a trap door out of pylwood and attached 11/2" styrofoam to the under side.

Hope this helps..good luck.
Click to expand...

I tried your method of centering, got it centered, (wasn't before) and darn, it still leaks steam. The water was 190 degrees.
 
Sawyer said:
Extremebison said:
I'm looking at the GARN at the moment for my heating needs, very early stage of development. But my thoughts or to use the spray kits to coat the holding tank especially the top and lid, if I were to purchased one of these units. A one inch thick coat over the whole tank of the unit, excluding the front would offer a huge savings in btu's savings in years to come. The kits allow you to do it yourself. I think it would be worth the extra $ to have the unit sprayed foamed. I'm little spray foam pro active. Everything I build seems to get sprayed sooner or later. I'm surprised to that GARN does not sell them all sprayed up.

Sawyer I've been reading and watching your posts, making me want to take the GARN route. Very expensive but at the same time the savings and simplicity would be worth the effort, in years to come.
Click to expand...

Garn specifically stated when i bought mine that it should not be foamed nor should cellulose be used. I think it had to do with a reaction to the metal. The manhole cover is aluminum so it would be ok.
Click to expand...
They must be talking a different game know. When I bought mine there was no talk from them about not foaming the garn. I foamed mine and I don't see were their would be a problem. I would be more scared of another type of insulation getting wet and never drying out and that could rust the tank. I have friend's that have had metal building spray foamed for years and never had a rust problem. I guess we will see what happens. I love spray foam and have used it in a lot of applications and had zero problems with it.
 
Bruce, like you, I am going to build something to isolate the steam from the insulation, if not the fiberglass insulation could be compromised. I cut and threw out all the previous insulation that was damp. I have insulated the manhole cover with closed cell foam. After isolation I will also insulate the manhole cover with DOW blue board.
 
hedge wood said:
They must be talking a different game know. When I bought mine there was no talk from them about not foaming the garn. I foamed mine and I don't see were their would be a problem. I would be more scared of another type of insulation getting wet and never drying out and that could rust the tank. I have friend's that have had metal building spray foamed for years and never had a rust problem. I guess we will see what happens. I love spray foam and have used it in a lot of applications and had zero problems with it.
Click to expand...

If I had been told I could foam I would have had Dave that foamed my trench foam my Garn in an instant. I have the fiberglass insulating completed so I will leave it as is. Like you, my concern is the fiberglass must remain dry or rusting is possible and "R" value would be lost.
 
If the fire retardant in the spray foam is the problem, you could cover the garn with a thin non flamable reflective insulation prior to spraying, thus avoiding the foam to actually contact the garn.
 
Good idea Tom, that should solve any problems if there are actually any.

I seem to have found a position for the manhole cover that seals. I am now firing up to build temps to check.
With a 40 degree difference to the workshop (turned the thermostat up 4 degrees) and 20 to the house it is not as fast as I would like.
Temperature is 2 degrees with wind gusts to 35mph. Propane is stored safely in a underground tank. ;-)
 
About the manway cover, I slit a length of 5/8 inch foam backer rod and embedded the backer rod the depth of the slit ontop of the manway collar. that gives a larger conforming contact area when you put the lid on. backer rod is usally found in the masonry section at home depot. I bought a 10ft piece about 4$, enough to do the lid 2 times.
 
TCaldwell said:
About the manway cover, I slit a length of 5/8 inch foam backer rod and embedded the backer rod the depth of the slit ontop of the manway collar. that gives a larger conforming contact area when you put the lid on. backer rod is usally found in the masonry section at home depot. I bought a 10ft piece about 4$, enough to do the lid 2 times.
Click to expand...

Thanks for the great idea Tom! I will get some backer rod the next time I go to Home Depot I checked the collar today and the weld was smooth. I rotated the cover a few times and found a spot that seems to minimize the vapor loss. It may be the cover but hopefully your idea will solve this problem.
 
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