Open atmosphere Tank for a gravity hydronic system

heatingman_2

Hi I have a gravity hydronic system that is in need of an open atmosphere tank. The tank is about 12 - 14 in. in dia and 24 - 30 in. in height. It has 2 1" IPS tapings, one at the bottom and one at the top. It holds about 15 gallons of water. None of my supplies can get me a tank like this or know where to get a tank like this. Anyone know where I can purchase one, the customer does not what to upgrade their system.

Alan(CaliforniaRadiant)Forbes

I've never

seen a new one for sale; no one uses them anymore since it's much easier to cap the lines in the attic and install a diaphragm x-tank in the boiler room.



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Mike T., Swampeast MO

Possibly Something Like This?

Vertical Water Tanks

Larger than the size you state, but as long as you have room it won't matter at all if larger than required to take up the expansion room of the system. The "standard" connection locations look appropriate. As long as it's the highest part of the OPEN system it only has the pressure of the water it contains. Even though it's plastic, temperature shouldn't be any kind of problem as there is no pressure to speak of...

rich pickering

Our sheet metal guys make them all the time.Take your old one to a shop for a pattern.

Larry Weingarten

try this

http://www.mcmaster.com/ Page 1572. They have nearly everything!

Aidan (UK)

Open vented heating

There are lots of open vented heating systems in the UK, some with gravity flow to the indirect water heater.

The tanks used were rivetted steel galvanized after fabrication, until the 60s. Now they are generally 4-gallon plastic. The plastic has to be rated to withstand boiling water, in case there is a controls failure, and it has to be fully supported on a waterproof platform, not rested on joists. Boiling water in the tank is more likely if there's a wood-fired boiler involved. There is usually a float-valve to admit make-up water and the water level, when the system is hot, has to remain below the overflow pipe.

The link below refers to a fatal accident which occurred when the contacts in a thermostat controlling an electric water heater welded themselves together, causing boiling water to be discharged from the open vent pipe into an inadequately supported plastic water storage tank. The UK specification for electric immersion heaters has now been changed to include a secondary manual-reset thermostat.

http://news.bbc.co.uk/1/hi/england/cornwall/3038596.stm

Boilerpro_3

I'd close the system for the system's sake

> Hi I have a gravity hydronic system that is in

> need of an open atmosphere tank. The tank is

> about 12 - 14 in. in dia and 24 - 30 in. in

> height. It has 2 1" IPS tapings, one at the

> bottom and one at the top. It holds about 15

> gallons of water. None of my supplies can get me

> a tank like this or know where to get a tank like

> this. Anyone know where I can purchase one, the

> customer does not what to upgrade their system.

Boilerpro_3

I'd close the system for the system's sake

Open systems tend to create ever increasing corrosion, sludge and all sorts of nasties that will eventually start showing up as leaks.

Boilerpro

Aidan (UK)

Not necessarily

"Open systems tend to create ever increasing corrosion, sludge and all sorts of nasties"

There are lots of open heating systems in the UK which have run for many years with little/no maintenance. They are certainly less maintenance intensive than sealed systems. However, if they are set-up incorrectly, so that there's a regular change-over of water in the expansion tank, then the resulting corrosion can go through a steel radiator in 2 or 3 years and fill the system up with the black, sludgy corrosion products and/or limescale.

Many of the open systems are gradually being converted to sealed ones. I'm not sure that an expansion tank in the loft would be advisable in the weather some of you get in winter.