Expansion Tank

Kickbundler

I have a gravity hot water system in my house. The house was built in 1923 and originally included two expansion tanks (in the basement). Sometime prior to me buying the house, someone decided to remove the radiator from the kitchen and replace it with radiant floor board heating. In the process they removed the second expansion tank from the system. This baseboard heating doesn't work at all owing to the fact that the hot water needs to flow up and then down to heat the baseboard (remember, gravity system).



We are in the process of remodeling the kitchen and are planning to install radiators again. My question is whether we should reinstall the second expansion tank in the system. I would like to do this just to restore the system back to its original configuration and I assume the original engineers knew what they were doing. Will this increase the efficiency of the system? Why?



Thanks in advance

T.R.

Mark Eatherton

If it worked with one tank...

Why put the other tank back in line? Although over sized expansion tanks are the one component that doesn't cause any negative consequences by being oversized, but why do it if it is not necessary. What did your water pressure go to when it was really cold outside?



ME

Kickbundler

It seems to work OK with one, but....

I just assumed there might have been a reason for the original installers for putting in two. The system pressure stays low (~15 psi max) when the tank is properly drained (I had an issue with this a couple of years ago where the tank had filled with water and needed draining and resealing).



I'm not sure I need the second tank. Just wondering if there is an advantage.



Thanks

ecletrical

did you mean

baseboard, fin or cast, or a radiant floor. Tell me which and I'll tell you what I did to a similar system that works great.

Kickbundler

I meant

Fin. Copper tubing with aluminum fins housed in compact steel baseboard cover.

ecletrical

I'm not sure why the BB is not working if its

plumbed like a normal cast rad. However

on a similar gravity 2 pipe system I added a radiant floor where they didn't want a cast rad occupying space in the kitchen.

I took it off the take=offs that normally fed the old cast rad. I added a circulator and a strap on aquastat (near the boiler) so when things got hot the pump automatically started. It works great - to an extent - in that there is no t'stat for the kitchen and the rest of the large cast rads respond very differently. However they are satisfied, the floor is clearly warm.

Mark Eatherton

Over kill...

No technical advantage to having the expansion tanks over sized.



ME