Unpressureized storage protection?

[afblue]

So I have been reading through hundreds of old threads, and I havent seemed to come across an answer that is clear to me.

Does anyone regulate the inlet temp to their unpressurized storage?

Essentially if you have a Danfoss valve on the inlet of the boiler to maintain the boiler at 140+. When the system with storage starts to reach capacity, the inlet water to the storage is going to start climb above 180-190+. Would it be worth having a danfoss or Temovar valve that limits the inlet temp to the storage at 190F so you can charge the whole tank up to 180-190. I understand that stratification is a good thing, but with the limitations of a EDPM liner, I want to stop the tank from going over 190, and have a full tank of 180F that will stratify as I pull the heat out of it when the boiler is burned out.

 

[Nofossil]

Since you presumably have a heat exchanger between the boiler and storage, it will be very hard to get storage above 180 unless you're running a very high boiler outlet temp. I rarely get the top of my tank above 170.

 

[woodsmaster]

You should be able to turn the temp down on the boiler control if it gets to hot.

 

[afblue]

Well I guess thats the question, when the temp climbs up to the 180-190, is it sufficent enough to just control the boiler outlet temp. I am wondering iif its worth controlling the boiler going to idle based on the temp at the top of the storage or ar the bottom, to verify that the storage is saturated before the boiler idles.

 

[mwk1000]

For me, trying to get he tank fully charged to that level is not worth the wood it costs. I find that the exchangers performance drops off enough that I am refilling the boiler to push another 15 degrees into the tank when 1 1/2 loads starting from 100 will get me 60 degrees. I would rather put that load in - in the morning the 2-3 times a season it is needed. ie. -15 outside. Not Really the exchangers fault just the boiler is capped at 195 so the exchanger rarely has the temp differential to work with. ( I am sleeping and the fire is past its peak )

I am quite happy with 100-175 range. I will only help the edpm last longer.

1500 Gal EDPM DIY , w/eko 60 supplying 2 forced air propane furnaces Water/Air HX

 

[flyingcow]

I'm with mwk1000, not worth the wood to push it above 170ish. Once in a while i go to 180. You'll get used to how much wood to push it to about 170ish. In the summer I never plan on going above 170. 160-170 is usually the norm.

 

[afblue]

I think this is the real life experience I was looking for, I plan on designing my tank and system that I can run the house all the way down to 100F in the tank, and have the DHW on priority when the I fire the boiler. With a 820 gal tank running 170-100 thats still 476K BTUs which at max design load for my house still gives me 11 hours of storage, so I can fire the boiler before work, and when I get home and make it through the night with no issue.

 

[flyingcow]

Basically what i do is just that. Get home at night and fire boiler. Refill if needed. usually will be good until the next afternoon. My DHW coil is in tank. I can get a decent shower down to about 110 degrees in tank. The wife and kids kinda grumble, but they deal with it. What little I know about EPDM liners id anything over 170/175 is shorting the life of the liner. Which as we talked about, when you push that tank to 180, you use a pretty good bunch of wood. The only time I do that is on a cold, cold night. Also, my system is set up so when boiler is running and house calls for heat, it ships water from boiler right into baseboard. Doesn't pass thru the tank. Any excess heat will go into tank.

 

[Willman]

I can run the house all the way down to 100F in the tank

This is the secret to max efficiency of any heating appliance especially wood. Design to utilize lower temps and everything works out for the best. You should be commended on your due diligance. Its a lot cheaper to plan upfront rather than after the fact.

Will

 

[afblue]

I would like to have the whole thing planned by the time I get home from my 4 month desert deployment, but I have been waiting for 3 weeks now to recieve a book on modern hydronic heating that I ordered

 

[turbotech]

Where is the best place to order the EDPM liner? Is there a place comparable to dynamitebuys.com where I am ordering stove pipe from? Fast service and excellent prices.

 

[flyingcow]

Tom of Maine uses a different kind of liner. He doesn't use EPDM. The materials he uses withstands the high heat much better. The liner I've got can withstand 180's. He might chime in. His company is ion my signature.

 

[turbotech]

Tom of Maine uses a different kind of liner. He doesn't use EPDM. The materials he uses withstands the high heat much better. The liner I've got can withstand 180's. He might chime in. His company is ion my signature.

Do you have a rough idea of how much the cost was to add the tank?

 

[flyingcow]

Tom of Maine uses a different kind of liner. He doesn't use EPDM. The materials he uses withstands the high heat much better. The liner I've got can withstand 180's. He might chime in. His company is ion my signature.

Do you have a rough idea of how much the cost was to add the tank?

nope. contact him thru his company. Buy the whole tank and heat exchangers. They're pretty impressive. Works very well.

 

[Duetech]

Tom in Maine told me they can custom build a liner for round or square tanks of just about any reasonable size. If you already have a tank or something to use as a tank he can probably build you a liner for it. Thas the route I am looking at using an old out of use 500 gallon above ground tank.

 

[turbotech]

That is good to know that they make custom liners.

One thing I noticed is that their is not a lot of threads about tanks built out of wood. I was wondering why no one uses 3/4 plywood and 2x6 wood to frame and build a tank and insulate with R30.

 

[afblue]

http://builditsolar.com/Projects/SpaceHeating/SolarShed/Tank/Construction.htm

This is the article I am going to follow. with some mods to make a tank thats larger in capcity. I would rather mine be taller and have less of a foot print. What I have read is the most important thing is to have a layer of polyiso........ foam on the inside of the plywood, becuase if not, you dont create a thermal break, and the heat will convect out the wood frame members, since wood has like 1/3 or less the R value of insulation.

 

[tom in maine]

If you are going to build a wooden tank, you should consider building it out of pressure treated lumber and stainless fasteners.
Over the years, I have been involved in replacing wooden tanks that just let go, usually due to some rot somewhere since they are usually in damp basements.

If you prefer to build your own shell, also remember that the load on a tank is exponential as the depth increases. The good compromise is a 4' deep tank. This affords
good stratification and somewhat reasonable loading. Keep in mind that a gallon of water weighs 8.32 pounds.

 

[turbotech]

I agree on the 4' height. That is the max I planned on. There is no dampness right now, unless the tank itself causes saturation it should stay dry. I could get a couple sheets of 5052 and TIG it together, but I don't see why a simple wood tank will not work for a long time.

 

[afblue]

The main concern with standard southern Yellow pine would be direct contact with brick or concrete floor. if they are insulated from these with a sheet of rigid foam it would create a vapor barrier to prevent any rotting.