Need help with old hot water system

mdreyer93

Hello, I need help fixing an old hot water two pipe system in my house I bought earlier this year. I've attached pictures with mark ups to hopefully help (if you can see them...)



Basically, our system is currently off because before we bought the house someone stole the short section of copper pipe connecting the old steel type expansion tank. >:( I've tried to show this in the first picture. At first I was just going to try and reconnect it but then I got on this site and started reading stuff and I think I have some other issues.



I thought I might as well just connect a new diaphram type expansion tank while I'm at it but as you can see, my pump is on the return side of the boiler and my old tank was on the supply side after the supply already split. Should my new tank go where the old one was or should I put it before the pump on the return side? Also, my water supply comes in before the pump on the return side. Is this right or should it be at the expansion tank connection?



I also don't see any type of air eliminator on my system at all. When I connect a new tank should I do it through a spirovent or something? is an air eliminator OK on the return side? When I had the plumbing fixed earlier in the year I had them add a backflow preventer to the system water supply but I don't see any kind of pressure reducer or auto fill valve anywhere, just a gate valve where the water supply comes in.



How should I proceed? I had a pro out to inspect and he seemed to want to hang a diaphram tank up between the rafters off where the old one used to connect like you would for a hot water heater.



Thanks in advance.



Mike

Ironman

Air elimination

The old xtank was also your air elimination device. You don't want to install a diaphragm tank unless an air separator is also installed. Since the entire system flow MUST go through the MBR (micro bubble resorber, air separator) your gonna have some major re-piping. In that case, I would move the circ to the supply downstream of the MBR.



If you simply re-connect an open xtank, I'd leave the circ alone unless there were air issues at the upper part of the system.



What kind of emitters do you have? If they are c.i. rads, then you'll still have to manually bleed them even with an MBR.

mdreyer93

thanks for the reply

I have old column-type C.I. rads. I figured they would still need to be bled but knew a MBR was needed with the addition of a diaphragm tank. So does the xtank/MBR need to go on the supply side or could it go on the return side before the circulator? I figured I could open that union above the pump and connect a vertical spirovent there and a tee to a diaphragm tank on the floor left of the boiler. I don't remember if there is a union on the supply side before it splits and I'm a little less confident with moving the pump....



About simply reconnecting the old xtank, how do they work? I may be missing some other piece because from what I remember there is a tee coming off the bottom of the old tank with the supply coming in and up to the tank through the tee but with the other end of the tee opposite the supply open... Is something else missing? Do I need any extra valves, drains, etc. there? I'll try and post a pic when I get home. Simply re-connecting the old tank would definitely be easier for now.



Thanks again for the help

Ironman

Old Tank

There are several variations on those old tanks: some have special drain fittings, others don't. You could indeed connect it to a SpiroVent on the return as long as the pump is down stream of it. It would still be pumping away from the PONPC.



The water isn't quite as hot there as on the return, so the air is not released from the water as it would be on the supply, but it will still work. But again, most of your entrained air is going to the top of your rads.



If you choose a diaphragm tank, make sure it's properly sized. A Extrol 30 is usually undersized for an old system with large pipes and c.i. rads.

Paul48

Expansion

Funny thing is...you can never have to much capacity, but you'll know when you don't have enough. I have a high volume gravity conversion, and had to go with a #60 because the relief valve sputtered with the #30.

kcopp

The old style tanks worked well in removing air. If you keep the tank you can't install ANY air vents in the system or spirovent. It will water log the tank in short order. Just hook the copper back in and you will be fine.

icesailor

Its a good thing that they don't do them like that anymore. Its amazing all the old systems done like that that are still running fine today. Just amazing.

Re-Connect the old style expansion tank and let her rip. It will work. Probably still be working just fine when all the hot rod beer coolers are lined up on the curb waiting for the trash truck.

mdreyer93

Thanks all, I think I'll just re-connect the old tank and give it a go. My tank just has a tee coming out the bottom so I'm re-connecting it to the system supply on one side (with a valve in-between) and I'm going to put a sillcock/hosebib on the other end so I can drain the tank if needed. I think the vandals stole my old hosebib too. Does this sound right?

Also, just to double check for when I re-fill and start the system back up; I should close the valve to the old expansion tank at first while I fill, try and bleed as much air out of the cast iron rads as possible, then open the valve to the expansion tank once I fire up the boiler? Once the system is filled do I close the gate valve from the water supply or leave it open?

Please let me know what you think as I'm hoping to get it up and running this weekend. The system is drained now as we re-connect this tank and fix some other old black pipes and replace a radiator that had leaks.

jonny88

Dont want to derail thread,but whats up with gas line on water heater.Am I seeing it right?

mdreyer93

what about it? it's tracpipe from the ceiling. plumber put it in earlier this year.

RobG

John, it's the new style of Trakpipe called counterstrike I think. I have no idea why they made it black though.

Rob

icesailor

RobG said:

John, it's the new style of Trakpipe called counterstrike I think. I have no idea why they made it black though.

Rob

The "Black" part is high in carbon dust and is supposed to allow electrical current to easily flow through the covering of the pipe.

Stainless steel is a very poor conductor of electricity. So is the yellow plastic covering.

mdreyer93

Any feedback on the fill/startup sequence I outlined above? I just want to make sure I don't screw something up. Also, still wondering about leaving the fill valve open or closed? Thanks!