kurtswen
Northern NJ
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I found two of the four of my A/C's through bolts loose to the point the heads of the bolts were not touching the flange surface of the bottom plate. So I loosened them all up and snugged all four to about half a turn compression of the seal. I could easily add many turns and just crush the seal but I'm sure that is not how it is meant to work long term. So how tight should it be? By torque on the bolt or compression of the seal or by how many turns after finger tight.
Thanks in advance for the advice.
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hemlox
Western Illinois
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Just snug them up, you dont want to torque them, you kindof just get a feel on how tight. You dont want to over compress the seal. It sounds like you have them about right.
* This post was
edited 10/12/08 09:48pm by hemlox *
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Raften
Northern Calfornia
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I think what you did is right, just check them from time to time and adjust.
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mike4947
N. Syracuse, NY
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Don't hold me to it, but IIRC the "crush height" is 60% of the original gasket height. The problem is you don't know the original height when you go to retighten the loose bolts.
If the original instalation was correct and you find loose bolts (and you will on about a 1/3 of AC's) just tighten them finger tight without causing any more compression.
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Gale Hawkins
Murray, KY
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mike4947 wrote:Don't hold me to it, but IIRC the "crush height" is 60% of the original gasket height. The problem is you don't know the original height when you go to retighten the loose bolts.
If the original instalation was correct and you find loose bolts (and you will on about a 1/3 of AC's) just tighten them finger tight without causing any more compression.
In reading my install manual that came with the MH 15 years ago "crush height" was mentioned. If my units started leaking I would just snug all bolts an equal amount and try it and if no luck buy a new gasket. I would hate to get the old on out of the hole however.
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LarryJM
NoVa
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Joined: 11/09/2007
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kurtswen wrote:I found two of the four of my A/C's through bolts loose to the point the heads of the bolts were not touching the flange surface of the bottom plate. So I loosened them all up and snugged all four to about half a turn compression of the seal. I could easily add many turns and just crush the seal but I'm sure that is not how it is meant to work long term. So how tight should it be? By torque on the bolt or compression of the seal or by how many turns after finger tight.
Thanks in advance for the advice.
Below is from the installation and operating instructions manual for the Duo-Therm 600 series PENGUIN, 579 Series BRISK AIR, 590 and 595 Series QUICK COOL A/Cs.
Start each mounting bolt through the ceiling template
and up into the unit base pan by hand. Evenly
tighten mounting bolts to compress gasket to
1/2" this will be a torque of 40 - 50 inch pounds.
Larry
2001 standard box 7.3L E-350 PSD Van with 4.10 rear and 2007 Holiday Rambler Aluma-Lite 8306S Been RV'ing since 1974. TRAILER MODS
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TXiceman
(Near) Houston,TX
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Another issue is to tighten them evenly. The floor pans on the newer A/C units are pretty thin and can be warped if they are not snugged evenly. If you warp the pan, you might cauase the fan to hit the housing....yes they are that flimsey.
Ken
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wolfe10
Texas
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Re-torquing old bolts to a spec in new installation manual will likely get you incorrect gasket compression.
Many older bolts are rusted/corroded and therefore will give a false-high reading (due to resistance in threaded area vs actual compression of the gasket).
Better on older unit to just take up an 1/8th turn on them IF they are leaking. Gasket compression height is more important than bolt torque on older units.
And, with two people, replacing the gasket is really a fast easy solution. The roof unit is bulky, but not heavy.
Brett Wolfe
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jauguston
Bellingham, WA
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The Duo-Therm Brisk-Air 13,500 unit I am using for a conversion to a houshold 6000btu window unit in it has 2"X2"X3/4"white rigid foam blocks glued to the bottom of the pan outside of each corner of the seal to act as stop blocks. The seal is 1" thick. So that would be 1/4" of compression or 25%.
If you go to the thread "Converting a Window A/C to Rooftop RV unit" on page 7 there is a picture of the bottom of a Brisk-Air pan.
Jim
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kurtswen
Northern NJ
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Thanks for the help everyone. I wanted to pass on info I was able to find to awnser my question per manufacturer specs. On the interior of the vent system are tabs that show you how far to tighten down the AC unit. They are mounted to the upper plate and you tighten the four bolts until the tab touch the roof. They are plastic not metal.
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