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Better balance, better heat... starting from scratch? (a LONG post.)

TB_MD Member Posts: 7
First let me say that Classic Hydronics has been a real lifesaver.   Especially the part about bleeding - "if you're not getting any air, stop bleeding."   I'm looking for ways to improve the efficiency of my heating system and especially to get more even balance between the heat provided to different rooms.

I have a 1930s two-story colonial in Maryland with cast-iron radiators on a two-pipe, reverse-return system and a 1984 Dunkirk Boiler.   The radiators are on two circuits - one that goes to the rooms on the south and east; the other to the north and west.    There's two pdf diagrams attached of the distribution of radiators and the piping around the boiler.  (The mains and feeds to the radiators are all iron, but the stuff around the radiator is copper, probably from the mid-1980s replacement of the boiler.)

Heat has always been an issue.  Sometimes the radiators on one circuit

will be working; sometimes the ones on the other.  Rarely both at the

same time.  The radiator in upstairs bedroom (a 60" monster) can get so

hot it can't be touched.  Shutting off the (non-thermostatic) control

valves doesn't help. 

I'm doing some remodeling in the basement, so there's a good opportunity

to make some changes - even pretty substantial ones - if they can

improve the way the system works.  My experience with the plumbers and HVAC people who I've dealt with has not really inspired a lot of confidence.  I've gotten very contradictory explanations and recommendations and would like to have a more fact-based approach to this.  I've attached a couple of pdf's - one diagrams the piping around the boiler; the other the layout of radiators around the house. 

Some more specific facts and questions:

- I like the layout that Dan suggests on page 70, with the air separator and vent at the PONPC.  Would it be worthwhile for me to have the system redone on those lines?

- In preparation for the remodeling, the contractor's plumber cut off the pipes that went through an uninsulated crawl space and fed a radiator on an enclosed but completely uninsulated porch.  That actually made the remaining radiators hotter, but I think contributed to the balance problem.  He cut and plugged the pipes (a couple of inches after they T off to a radiator) but did not connect them.  Should the supply and return pipes be connected where they were cut? 

- One plumber told me that the reason the system was not balanced was because the arms of the T that comes off the radiator have to be perfectly symmetrical.  Mine are completely asymetrical - like 12 inches to one side and 36 to the other.  Is that true?

- There is a new circulator pump on the return side.  Would it be worth moving it to the supply side?  Or to have one circulator on each supply circuit?  

- If I am going to replace some of the pipe around the boiler, can/should be  some or all of that be done with PEX oxygen barrier?

- The feed pipe for the radiator currently comes off the same line that feeds into the hot water heater.  The feed into the hot water heater and the rest of the plumbing are being changed from (leaky) copper to PEX.   Should the section of pipe that goes to the boiler be oxygen barrier PEX?

There's probably more - and I'd be happy to post pictures and more details if needed - but I'm grateful for the help.  This is my first house on the East Coast.  I grew up in California, lived in condos and lived in (very elegantly and efficiently heated) homes in Germany and Eastern Europe.  So the cost of heat and the way hydronic systems are designed and maintained has been kind of a shock to me and my budget.  

Any advice and suggestions - from the trivial to start-from-scratch - would be welcome and considered...



  • TB_MD
    TB_MD Member Posts: 7

  • Zman
    Zman Member Posts: 6,989
    Double post

    I see you have your system posted twice. I think this one gives more details of your system. As Ice and SWEI pointed out you are piped direct return not reverse return. The water is lazy, it just keeps taking shortcuts. With reverse return the water has to travel the same distance to get to every radiator. This naturally balances the system. To convert yours to reverse return, you would run a new supply or return from the boiler to the end that is presently capped. The existing supply or return would be capped at the boiler end. You need to reverse the direction of flow in the main on either the supply or the return.

    Pex with o2 barrier would be suitable for the run. I would still use iron or copper near the boiler.

    It would be best to pump away from the expansion tank.

    With iron radiators and a boiler almost 30 years old I would consider a Mod/Con boiler with outdoor reset. The boiler owes you nothing and those radiators would work great at lower temps. I would expect savings of 30-40%. If you are going to put the work into the repipe why not save some money. I am a huge fan of Triangle Tube boilers. I would recommend any boiler with a fire tube exchanger.

    Thank you for the thorough post.  I hope this explanation helps.

    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • TB_MD
    TB_MD Member Posts: 7

    Sorry about the double post.  I thought this one had too many different questions so it would make sense to break it down into individual pieces.
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