expansion tank removal

david byrns

We have a 1920's hot water system. The 2nd floor bath has a 3ft tall expansion tank in the top of the bathroom closet. We are remodeling our bathroom and want the expansion tank removed. Is it safe to cut the pipes, and move this tank up to attic - or - should I buy a new expansion tank? If a new one, what should I purchase?

Also, this bathroom has a large radiator which I would prefer to remove. Is it possible to "convert" this so that we would have the hot water underneath the tile floor, for floor radiant heating?

Any comments would be appreciated

Michal

you can do a few things

well a few things I can think of is to remove that tank and install a diaphram tank near the boiler such as a extrol tank, you will have to figure out the size depending on system volume. do not put it in the attic as it might freeze up, then you are asking for alot of damage. to do a radiant floor you need to install a manifold and run the piping as such, this might require alot of piping just to accomplish that, hard to tell without seeing it. You can do a kick space heater under the vanity if you have one or one recessed in the wall. My honest opinion is to run cast iron baseboard along the outside wall, because with all else (besides radiant) it will be drafty and cool. You can also opt for a electric radiant floor, I have seen these put in on a thermostat of their own, but I am not nuts about them. hope this helps a bit, I am sure other guys might have more comments

Mike T., Swampeast MO

Expansion tanks as the highest system element are part of a gravity system. It was probably put in that closet to avoid any chance of freezing in the attic.

Is your system still working under gravity power? (Look for a circulating pump near the boiler.) If so, I think you really need to keep the tank as the highest element. Gravity systems are open (you should find a pipe leading out the roof or eave from the tank). Closing the system with a modern tank might cause circulation problems.

If you find a pump near the boiler, your system has been converted to forced flow. Usually the old tank was removed at that time and replaced with one near the boiler.

Be VERY, VERY careful if you want to replace that radiator with something else! Unless the bath currently overheats, you face extensive and expensive piping and control changes to maintain the balance with a smaller (or different style) of heat emitter.

david byrns

Mike, thanks for your response. Yes it is a gravity system. No pumps. The overflow goes into the attic and then down through a pipe the walls and into the basement drain. I've only seen it overheat/overflow once, but recognize how important this is. My attic isn't too cold. I really want an opinion as to whether an 85 year old steel tank should be kept or when I move it to the attic should I replace it with a 'new and modern' expansion tank. My tank is 1 ft in diameter and 3 feet tall, and maybe I can find one 3 feet wide and 1 ft tall, so it can stay in the bathroom, but drywall around it. Any opinion? Thanks again.

David Byrns
Webster Groves, MO.

Mike T., Swampeast MO

The modern tanks are compression (as opposed to expansion) tanks designed for sealed systems. Gravity systems are still open to the atmosphere. They are not pressurized so the tanks tend to last a VERY long time.

The tanks are tall and narrow so that you can use your altitude gauge on the boiler for replacing water that evaporates. If you replace with a short, fat tank you'll have VERY little leeway...

As long as your attic isn't extremely leaky and only insulated at the floor level there shouldn't be [much] of a freeze danger in the St. Louis area.

Unless you're already planning on changing to forced circulation, DO NOT replace the standing radiator with baseboard (or worse yet a radiant floor). You WON'T have enough motive power for sufficient circulation and heat.