How hot will my storage be?

[Birdman]

I am hoping to install storage soon for my Tarm Solo Plus 40. I have a basic idea of how storage works... but very little idea of the specifics. Currently I have parallel hook up with a oil boiler. I love the system. My only issue is that when I have 3 zones calling for heat at teh same time... even when the Tarm is up to temp my oil boiler will come on. I was instructed to close teh valve( forgot its name) halfway and I did this. Anyways... this is not my issue... it only occurs once in while which is fine. My question is this. Will the storge water be hot enough to meet my needs? Often when my Tarm is running only one or two zones will call for heat.. .which is great because the water is really hot then because it is not mixing with alot of return water. I love it when my living room zone calls for heat and it is the only one calling.. because then i get real hot water sent to just that zone and it gets warmer quicker in the livingroom. SO... my question... when i have storage.. will the water in storage get hot enough? I like it when i look at my tarm gauge and i see it is at 90 C... cause then i know if a zone calls i will get real hot water to it. Does storage get that hot? With my system.. it seems the only usable hot water comes when the Tarm is at like... 76 C. I have 4 zones... 3 for baseboard and 1 for domestic hot water. SO my question again... will my storage get hot enough to help me?

 

[Robby]

I will relate my experience. I have a conventional boiler, hold 42 gallons of water. 9 zones ( one is DHW). At 180 F if too many zones called for heat the boiler could not react quick enough. I added 150 gallon storage. Much better, actualy worked OK. Then I happened to find a 1200 gallon, perfect pressure tank. Plumbed boiler to tank, bottom of tank to input of boiler etc. and heat draw direct to tank, hot out the top and return in bottom. I store at 190F and use down to 150F. Everything works perfect. All the heat in the world. Boiler also runs much cleaner and more efficiently. I do not see why gassifier would be any different. I do not know what the ideal gallon-age of storage is, most likely depends on BTU draw and a dozen other things. But simply any storage is better than none.

 

[Nofossil]

How is your living space actually heated - baseboards, radiant, hot air? It sounds like you need more heat exchanger in your zones. You should be able to keep your living space warm with water well below 180 degrees (80C) on all but the very coldest days. The more living space heat exchanger you have, the cooler you can run your water and still be warm. That will increase the effective capacity of your storage.

If you really need to have water at 180 degrees or more to be effective, then pressurized storage is the only option. You can't afford the temperature drop that a storage heat exchanger would have.

 

[rkusek]

I will relate my experience. I have a conventional boiler, hold 42 gallons of water. 9 zones ( one is DHW). At 180 F if too many zones called for heat the boiler could not react quick enough. I added 150 gallon storage. Much better, actualy worked OK. Then I happened to find a 1200 gallon, perfect pressure tank. Plumbed boiler to tank, bottom of tank to input of boiler etc. and heat draw direct to tank, hot out the top and return in bottom. I store at 190F and use down to 150F. Everything works perfect. All the heat in the world. Boiler also runs much cleaner and more efficiently. I do not see why gassifier would be any different. I do not know what the ideal gallon-age of storage is, most likely depends on BTU draw and a dozen other things. But simply any storage is better than none.

When you are gone for a couple days, how long does it take with your boiler running to start generating heat in the house? I was going to plumb the boiler and storage as secondaries of a large underground insulated pex primary loop between my house and barn but Gooserider suggested something like what you are doing instead. Your method seems to have many advantages and only question I had was about the cold startup times.

 

[flyingcow]

I used all the controls/valves that tarm recommended (and yes sold me). A little pricey, but works great. All i know is I've got decent use of storage for having primarily BB for delivery system. As nofossil asked, What your delivery system?

-With my set up, from throwing the match in the boiler, I'll have 165 soon to be 195 water temp running thru my baseboard in about 45 minutes. When the t-stat is satisfied, dumps remaining heat in tank. Can heat my house and tank at the same time.
-
Take me all night to describe controls(because i drive truck, not install heating systems). Look at Tarms info. Termovar valves is what they use, look at the diagram. My storage tank - click on the link in my signature.

 

[Robby]

Hi huskers,

I store water at 190F, it used to be 180 but when I found out Garn used 190F or more I could see no reason not to follow. With just shy of 1400 gallons over run is of no consequence. I have two water to air exchangers, 9 steel radiators and coil in 80 gal. DHW tank. All will heat with water temp down to 140F, just takes a little longer. That means I have about 580,000 BTU stored. Because we have animals, in real cold weather someone is always around the farm. In summer 4 or 5 days is not a problem. Depending on temps we usually only burn daily except in coldest times.

I have found that even below the 140F there is enough heat to keep us warm, but boiler must run for extended time to supply residence and bring up storage temperatures. I have even looked at storage at 200F but decided it was not needed, works OK as is.

If anyone reading this knows, can you tell me how much the boiling point is raised by pressure. Because there is 19' elevation difference between highest point of water in boiler blg. and bottom of system in basement I run 20 PSI static.

 

[kabbott]

Hi huskers,
If anyone reading this knows, can you tell me how much the boiling point is raised by pressure. Because there is 19' elevation difference between highest point of water in boiler blg. and bottom of system in basement I run 20 PSI static.

@20 psi boiling point we be about 260F but I sure would not want a large storage tank in my house over 212, if something fails and you loose pressure
it can flash to steam. In other words IT GOES BOOMMMMMMMMMMMM! :ahhh:

 

[Robby]

Thanks,

The tank is outside, but I don't intend to run any higher temps. I now have boiler overheat dumping into house, but I could just use tank. It never over runs now, but if something failed, who knows. Because I am anal retentive I have my own low tech safety.
Ordinary snap switches on chimney and on top of water on boiler. Anything over 210F on boiler, manual re-set snap switch turns on pump and very loud horn. I know, over kill, but it makes me happy.

 

[Birdman]

So... I have 4 zones. 3 for baseboard heat. 1 for hot water. If I get storage.. and i can heat it to 180.. will the 180 heat go directly to the zones?... or will it mix with return water as my system does now and create a lower temp that flows to the zones?

 

[flyingcow]

My storage is hooked right into the existing heating system. My storage will feed right into the baseboard. I take my storage up to 180, i get 180 feeding into BB. When the tank is down to 130, I get 130 into BB. My 1 zone for radiant, mixes to what I have it set for. Which right now is 125.

 

[Nofossil]

So... I have 4 zones. 3 for baseboard heat. 1 for hot water. If I get storage.. and i can heat it to 180.. will the 180 heat go directly to the zones?... or will it mix with return water as my system does now and create a lower temp that flows to the zones?

Well, as usual it appears that there's something I don't understand. Your comment about mixing with return water seems wrong. With a baseboard system, the baseboards should get straight unmixed hot water from the boiler outlet. Could you sketch a plumbing diagram and post it? Computer aided drafting is not necessary - crayon on a napkin photographed with a cell phone will do in a pinch.

Here's a picture of what I would think of as a 'parallel' system. Whatever the boiler outlet temp is, that's what he baseboards get. I'm assuming yours is different in some way.

 

[Birdman]

I went home and looked at my set up again. Honestly... I am really not an expert. I looked at the Tarm manual and looked at my sytem. It is set up exactly like the " parrallell" diagram in the manual. I am assuming ( when i do this i am often wrong) .. that based on the manual description that the hot water from the Tarm mixes with return water from the zones ... this happens at teh bottom of my oil boiler( where the Tarm pipe and the return water pipe both come together and then enter one pipe going into the oil boiler?... and then the water passes up into and through the oil boiler. The oil boiler has the controls on it? Do I have it backwards?