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Old house. Disconnecting a hot water heating zone

Tom55 Member Posts: 4
Hi. I'm new to this forum. I've read some posts on this topic but was hoping to get some advice considering the unique topology of my hot water heating network. I'm going to put in an interior (French) Drain (FD) in my basement and will need to remove the baseboard radiators to do the job right. I'd like to solder caps to the feeds to the basement radiators while doing the FD job and so have to get all the water out of them. The house is old and so each of the three heating zones were plumbed differently. There are no zone valves for any of the three zones and and only one of the zones (C) has a manual shut off valve. Flow Control valves are used on all three zones. I've attached a schematic of this plumbing circuit to talk to the details of this setup for me. I'll also add additional info on those Flow Control valves at the end of this problem description.

I'm expecting that I will add manual Shut Off Valves (SOV) to the feed and return side of the basement heating zone
( Zone B ) which I'm looking to disconnect.

So I have three areas of concern that I was hoping to get some advice on:
1) Draining the system enough to allow extracting those radiators from Zone B while also putting in those SOV's.
After turning off the boiler and letting it cool down, I expect to open the SOV_SYS valve. After that I'm a little unsure.
Zone C SOV's will be open. I expect I'd open the FC valves if thats possible. Would I want to close the Expansion tank
2) If the system is drained I'll solder in the shut off valves for the source and return sides of Zone B (SOV_B_1 and
SOV_B_2). Any advice on how to make sure these copper lines are dry enough to solder in some new components?
Enabling soldering of caps on the Zone B radiator feeds is a similar concern.
3) Lastly, once I get radiators of Zone B disconnected, and new SOV's in place I'll have to bring the whole system up
and bleed it. I've read a few descriptions of how to do this, but in all cases folks were working with SOV's and Drain
Valves (DV) on all zones. Zone A in my configuration has neither and I can't add them in because that path uses
large steel pipes rather than small copper tubing. I can bleed Zones B & C since at this point both will have Shutoff
and Drain valves. While I'm doing this Zone A will be open though. Also, the radiators for Zone A aren't baseboard
and have bleeder valves so once everything is up and running I can use those to focus on bleeding that zone. Still,
I'm not sure of what my strategy should be here and would appreciate any advice.

Here's the additional detail on those Flow Control Valves on the feed side of the zones:
Zone A (FC#A) : RA Thrush & Co; #114A Flow Control Valve; Patent Reg 19873
Zone B (FC#B) : RA Thrush ; # CB114
Zone C (FC#C) : ITT Bell & Gosset; Flow Control Valve; SA-3/4 ; Model B19; P/N 107022 ; F00600 on casting

And here is the schematic and some pictures of the system.

Thanks for any advice. - Tom


  • STEVEusaPA
    STEVEusaPA Member Posts: 6,132
    edited September 2019
    It could turn into a big job. I guess the first question is how much repiping are you interested in doing? Because in reality all the near boiler piping is pretty brutal and would benefit from a repipe. Of course the boiler is near the end of its life too. A properly sized, properly piped boiler would be much more comfortable and save money in operating costs. You’re boiler is probably sending half of what you burn up the chimney, if not more...

    Your schematic doesn’t match the pictures, or is the schematic what you want to be your final design?

    If you’re cutting the system open, it’s a good time to repipe and set yourself up for an easier boiler replacement.
    —Design change considerations—
    1. Replacing the energy hogging circulators with modern circulators that use 1/20 of the energy.
    2. Switch to a 'pumping away' design.
    3. Isolation flanges on the circulators.
    4. Every old gate valve is leaking or going to leak if you try to use them, so either re-pack or replace with ball valves.
    5. You shouldn’t have your boiler feed going into the suction side of a circulator that’s pumping toward the expansion tank.

    As far as soldering/water, easiest would be to use a jet-swet. Easier, quicker, but costlier would be to make friends with someone who owns a ProPress.
    For temporary capping I would use shark bites if possible.

    Another note, you’re barometric damper is installed incorrectly for oil, needs to be on a proper collar on the straight pipe, then an elbow into the chimney base, doesn’t look like it would fit after the elbow. It also needs to be min 24 gauge.
  • Tom55
    Tom55 Member Posts: 4
    Thanks for your input Steve. Greatly appreciated.

    Wrt schematic vs hardware correlation - The schematic does include the two shutoff valves (SOV_B_1 & SOV__B_2) that I intend to add to the Zone B circuit. I do note that these are designated "adders" in the schematic. Also, I didn't show the cold water input circuit for the domestic hot water zone in the schematic. Other than that I'm not sure what I missed. I'll review correspondence later today.

    I will strongly consider re-piping and replacing the boiler but for now just want to enable my work on the french drain by isolating out those basement radiators. Every couple of months we have an inch of water in the basement and its a hot item with the rest of the family (my clients :) ) right now.

    So, if I do a system drain to set myself up to add those SOV_B_* valves is it simply a matter of opening the DV_SYS valve (which is at floor level, so a low point for the system) or do I need to muck with those Flow Control valves downstream from the boiler?
    Also, during that drain, should I isolate off the expansion tank via its Shut Off Valve (SOV_EXP) first?

    I'm still digesting some of your piping improvement suggestions and so will be looking into them closer today. I appreciate the advice and will look into implementing them once I eliminate that creek effect thats filling our basement every heavy rainstorm.

  • STEVEusaPA
    STEVEusaPA Member Posts: 6,132
    Your schematic shows the boiler fill going into the return at C, then nowhere. Does that pipe then go into the other C at the circulators?
    Is your expansion tank piped off of a flow control on one of the zones?
    For draining, I would drain the expansion tank so I could re charge it. If you have an AirTrol fitting it would make it easier. If not I would close the exp tank valve, fill/purge/bleed the entire system, then open that valve and recharge the tank while maintaining system pressure.
    If your flow control valves are working, most of the system water will be held in suspension.
  • Tom55
    Tom55 Member Posts: 4
    Thanks Steve. My schematic was off wrt that Zone C branch that was being fed by the Boiler Feed. That cold water fill branch goes towards the sunroom (Zone C) physically, but it feeds the outdoor spigot that is located on the exterior of that room. So, not a part of the heating zone circuits.

    Per your question on the piping of the Expansion Tank - yes it is piped off of the flow control valve for Zone A (FC_A). So the schematic is accurate concerning that aspect of the design.

    For the system drain then I'll include the expansion tank per your instructions. Also, sounds like aside from the expansion tank I should be able to conduct the system drain just using the system drain valve DV_SYS.

    For some completeness I'll add a couple of extra pictures here to round out the views of the system.

    Thanks for your time and help.


  • STEVEusaPA
    STEVEusaPA Member Posts: 6,132
    You win!!!
    Most amount of fittings from oil line to fuel pump. I count 16 potential leak paths from flare to pump cover...

    Along with the flue pipe I mentioned earlier, your fuel line doesn't meet code either. Not surprised based on the sticker on the side of the boiler.

    Well the good news is you can stick your whole head in there to clean it, so keeping it at sweet 45% efficient with 55% going up the chimney is not a problem. :)
  • psb75
    psb75 Member Posts: 699
    Age of that installation? 60?
  • Tom55
    Tom55 Member Posts: 4
    At least for the boiler and Zone A. I'm not sure when the other two zones were added in.
  • Brewbeer
    Brewbeer Member Posts: 616
    psb75 said:

    Age of that installation? 60?

    I had one of those in my last house which was built in '55. It got replaced when I moved in 20 years ago.
    Hydronics inspired homeowner with self-designed high efficiency low temperature baseboard system and professionally installed mod-con boiler with indirect DHW. My system design thread: http://forum.heatinghelp.com/discussion/154385
    System Photo: https://us.v-cdn.net/5021738/uploads/FileUpload/79/451e1f19a1e5b345e0951fbe1ff6ca.jpg