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-   -   Replacing my furnace... Confused on Diaphragm vs closed... (http://www.diychatroom.com/f17/replacing-my-furnace-confused-diaphragm-vs-closed-34452/)

nperkins 12-26-2008 06:17 PM

Replacing my furnace... Confused on Diaphragm vs closed...
 
So I am about to replace my furnace... Everything seems straight forward, i'm just a little confused on one part... I am trying to figure out if my old furnace is a diaphragm type, or Closed circuit type.. I have Hot water baseboard heat, and there is a taco makeup valve on the out line to the house. There is also another 3/4" line coming out of te top of the furnace that goes to a large cylinder mounted above the furnace.. Now I know its an expansion tank, and would assume it has a diaphragm, but it DOES NOT have an air pressure fitting on it... Only a drain petcock.... My new furnace (Weil McClain WTGO Gold) has a tapped hole on the top of it, with a sticker over it that says "Air elimination tapping at this location"... Do I have to buy an air elimination kit? Or is that what my expansion tank is for? Should I buy a new Diaphragm tank similar to what i see in most houses these days? Here is a picture of my current furnace... http://nperkins.riotdesigns.com/house/img024.jpg http://nperkins.riotdesigns.com/house/img025.jpg TIA

kennzz05 12-26-2008 06:22 PM

yes replace the tank with modern diaphram tank

nperkins 12-26-2008 06:23 PM

What is the current setup that I have? I had a friend who does alot of home improvement come over, and stare at it like a monkey doing a math problem...

yuri 12-26-2008 06:36 PM

Tell the monkey it is an open (non diaphram) expansion tank. Get the bladder/diaphram tank and it works much better/never leaks or gets waterlogged. Very good choice of new boiler. Get a proper combustion analysis/setup done on it so its works at its max efficiency.

nperkins 12-26-2008 06:38 PM

How much should that cost? The house is 850sq ft, possibly upgrading to about 1300sq ft in the future... a 2 gallon should be plenty, right?

yuri 12-26-2008 06:40 PM

Not sure. I would have to ask one of my plumbers. Maybe one of our other guys knows or post on the plumbing chatroom at top of page.

SKIP4661 12-26-2008 06:57 PM

You will probably need a #30 extrol tank and yes you will need an automatic air elimination set up on top of the boiler.
You may want to consider a secondary aquastat and a low water cut out also

hvaclover 12-26-2008 07:00 PM

Since when is a a boiler a furnace? Like calling a water heater a HOT water heater.

yuri 12-26-2008 07:29 PM

My call center calls everything a furnace and has no idea where Canada is.

nperkins 12-26-2008 07:33 PM

Quote:

Originally Posted by SKIP4661 (Post 202751)
You will probably need a #30 extrol tank and yes you will need an automatic air elimination set up on top of the boiler.
You may want to consider a secondary aquastat and a low water cut out also

By Secondary Aquastat I assume you mean a cutoff for the high limit... Wont the relief Valve take care of this? And I have a Taco Makeup valve that will be on the makeup water... This should eliminate the need for the low water cut out, yes?

hvaclover 12-26-2008 07:33 PM

i don't do hydronic so i used to have to qualify if it was a boiler or forced air.

Some people ain't got a clue.

nperkins 12-26-2008 08:15 PM

So I'm going to pickup an Extrol #30 tank, then do i need an air purger? Or since i'm putting in an air elimination kit on the furnace itself do I even need it? Or do i even need the air elimination kit since the air purger would be higher than the elimination kit? And this should work for the air elimination kit, right? http://www.plumbersurplus.com/Prod/W.../22800/Cat/224


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