Open or Closed cell spray foam?

Closed cell in that app would work best, it will need to be 2 lb foam or greater to achieve a moisture seal. Open cell would allow moisture to migrate. A word of caution if the tanks are bare metal it would be advisable to coat them first to avoid any reaction that may oxidize & cause corrosion under the foam where you cant see it. As well contact your installer & get the temp range for applying the foam, bring your tanks up to a temp in that range. Too hot or cold is bad for the reaction that happens in the foam after spraying, as the two parts that are mixed at the spray nozzle need to expand then cure, all in the right temp range. BTW if these are DIY tanks go ahead, however if they are some type of uninsulated factory tank call ahead to ensure you are not voiding any warranty.

I have used the DOW 2 part spray foam kits to spray the joist bays in my house. I would recommend heating the tanks up what the foam manufacturer says and it will give you the best cure. Most DIY foams like Tiger foam and DOW have an operating temp of up to 200F.

If I was to redo my tank foam I would contract it out. It is an expensive product. If you run into problems your stuck. If you contract for 2" or 3" for example you will get that for an end result.
The learning curve is steep as the other posters mentioned. Spraying onto steel adds extra difficulty. When spraying on steel it is not uncommon for the contractor to put down a base coat to isolate the steel, then overcoat for final depth.

I totally agree with ROBC. I bought the $300 kit from a building supply. Sprayed 3/4 of the joist bay ends in my house and ran out. Bought another $300 kit, to finish then ran around the basement trying to guess how much was left to finish off the 2nd kit, and get an even coat around the whole house. I would entertain someone giving you an estimate, and it might be fairly reasonable since they are spraying an single area than you may be able to buy kits to spray on your own. The learning curve is huge! Its like spraying 3 dimensional paint, and for doing it the first time you will end up with layer, 2-8" thick.

Frozen Canuck, I hadn't considered having the tank within a certain temperature range when spraying closed cell foam on it. I was going to spray the tank at room temperature, when it is still empty. Any idea about approximately what tank temperature should be planned for when spraying? I guess I am tyring to figure out if I should spray the tank after it is filled with water and everything is up and running, or before the tank is filled with water at room temp, as I had planned.

Mike

I had mine done after up and running.I did let them cool down to about 100f. Mine are up against a wall that is a heated space. I put 2 inch foam board on the top bottom and back. When they spray foamed they stuffed batts of insulation in the areas they could not foam, but sprayed o
ver the batts to tie every thing together I paid for a 2 inch job but anice tip to the installers got me 5 to 6 inches in spots
for an average of 4 inches over all. When my tanks are at 190 the outside of the foam is about 75 to 80.

Consult the spec sheets for the foam you are using, the application temperatures should be clearly written in those sheets. Follow them, they are arrived at through testing & more importantly "jobsite failure analysis" as these foams are applied in such a wide variety of conditions. Never spray a moist, damp, cold, or frozen surface of any type as the foam will not bond & will cure improperly if at all.

AFA before or after fill goes, definately after as this will give you a chance to check for & repair any leaks on your tank fittings, recommend that you get your tank up to temp/pressure & allow 48 hrs for those tiny little nuisance leaks to show themselves so you can remedy them before foam goes on. If you have not already done so, install approx 8-10" nipple on all tank fittings then valve then union, that way you never have to disturb the foam & can isolate the tank if you want to change plumbing in the future.

I have been giving Ricks thread about his Garn a lot of thought & I feel that we should all, when doing a foam on our system use as "auto default" a high temp foam, save us all the hassle of a redo if we ever boil the thing, as most foams will breakdown at high temp. Too much money involved in these things to not go that little bit further & get a lifetime of "forget about it" insurance for doing so. So respectfully I would like to change my recommendation to always use a high temp 2 lb or better foam when foaming parts of a water boiler system. The cost will be a few % higher vs normal 2 lb foam but the value of a lifetime of "forget about it" well...that's priceless.

We have to remember that if we get these systems right, use the right material, etc. They will in most cases outlive us. Think about how many 80+ year old steam boilers there are still in use today all built by generations of "DeadMen" that believed in getting it right & that short cuts were for fools & those who wanted to look for a new job.

AFA the statements about contracting this out I agree 100%, spraying on foam is not an easy job, not even close. If you dont agree hold about 5 lb at the end of your out stretched arm, thats approx the weight of hoses, gun & chemicals in the hose. A pro installer is also going to bring a great deal of knowledge & experience with him to each job, that alone could save you a bundle if say conditions are "not right" & you go ahead & spray without knowing & then have to replace it all.

I did mine with three inches closed cell and it works great, although it rarely goes above 190. I did leave a section exposed as the tank is in the basement and it keeps it pretty toasty down there, it just like a giant radiator. I wouldnt get the tank to hot before spraying, around 85 to 90 would be good. If the installer puts the foam on to thick with a 190 degree tank the foam will split do to the exothermic heat of the foam and the temp. of the tank. A 1" pass and let cool( this will be determined with the tank temp.) before the next pass would be the proper way to do it.

Thanks for the advice Frozen Canuck, henfruit and coolidge.

Mike

Treatment as you call it can be as simple as a good coat of primer on any bare metal, making it much more difficult for any corrosion to form when the foam is sprayed on the tank as the foam is moist when applied, it (later) cures to a dry surface but during application there is moisture available to start the oxidation process. If it were (oxidation) to form it would be under the foam where you cant see it & would likely progress to a very unhealthy state (for your tanks) before you noticed the corrosion. As above any surface being coated must be within the temp range for the foam that is being applied, if it is not you could slow down or even stop the exothermic reaction that both bonds & cures the foam. Very bad in either case.

jimdeq said:

Thank you all for your imput. My friend just bought a spray foam rig and has just begun doing a few houses. I will show him this post and see what he has to say. I was not aware that people pre treat steel tanks. What do they treat them with and is it a necessity if the tanks are the correct temp for the foam being used.

Click to expand...

I think a professional system will give better results than a DIY self contained kit, which will also let the installer fine turn the spray application where the 1 time DIY kits once they open and you start spraying, you get what you get. The spray tanks said they operate best between 75-85F so I would think you want the tank to be heated up to those temps, and like canuck said, I would connect everthing and pressure/leak test before you cover it in foam.

The foam kit application temp and the surface your spraying it on are two different things. Yes the foam does have to be warm to apply that is why the pros have heated hoses going to the spray gun.
The surface your spraying it on is different. Spraying on steel is unique in that the steel will suck the heat out of the foam as it is trying to cure. That is the reason for the base coat.
If you were to heat the tanks specifically for the foam application, I would think you would want to, or could be, be higher than 80F. Heating the tanks would also drive off any moisture.
You may want to consider putting armorflex insulation around pipes and fittings before they foam over. If you need to get at them in the future you can dig them out easier.

I had an insulation contractor spray mine- outside, in the summer. The benefit to this was that I could roll them with the tractor so they are pretty evenly coated all around. We then moved them into the basement on Dollies- which was pretty simple.
As for the connections, I had 6" nipples in all of the tappings wrapped in plastic & taped off ( pressure tested first) Once in place I cut the plastic just above the foam for a neat appearence.
Keep in mind the key thing that will take heat away from your tank is air flow which is why I wanted them sprayed all around. If you want some heat in the space, plenty will radiate off of uninsulated piping. A boiler mate, superstor, etc though only heated in 120-140 range has typically 1" of insulation, and is always cool to the touch.
I haven't tried the kits yet, always had jobs big enough to get the contractor out, but.. I have some smaller projects coming up that I will try them. My insulator ( the owner) claims that they gauge usage by the cycles of the pump on the truck, and so he can tell if the installer is spraying more or less than he should. I imagine the product to be quite expensive.