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Thread: Hot Water System Dilema

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    DIY Junior Member jasonnewyork's Avatar
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    Default Hot Water System Dilema

    I bought my house last summer, 2 story cape (1200sqft), with a gas fired hot water heating system. There are cast iron radiators throughout, with the exception of two rooms that the previous owner repaced with baseboards.

    To make a long story short, I hired a family friend (plumber) to convert the system to a 3 zone system (each floor is a zone). At that time, I didn't know anything about these systems and trusted him . He cut out the existing system (x2 1" supply/return pipes) and replaced with 3 zone valves with 1/2" PEX piping.

    During the past winter, I noticed a hugh imbalance. The first half of the first floor loop was extremely hot and the second half was cold/warm at best. The second floor, being only about 300sqft was OK and the basement is gutted with no heat so cannot comment.

    I'm in the process of finishing the basement and realize I need to address this issue. I had one plumber come out and suggested a I add another zone to the first floor but I don't think that is the right way to fix this. I'm afraid only way to fix this is to restore the old system.

    My question is do you think the best system was the original? From what I have been reading, seems like monoflow/2 pipe systems are best for cast iron rads while series loops are for baseboards? Another question is should I restore 2 pipe setup or go with a monoflow setup? My neighbors house is identical and all original from 1941. I went into her basement last night and confirmed the 2 pipe system. It appears she has all regular tees, I found no markings for venturi, monoflow, etc? Is that possible that a 2 pipe system use regular tee fittings?

    Any help is appreciated. I'm a bit lost right now and looking for some advice!

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    DIY Junior Member jasonnewyork's Avatar
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    Let me add the following:

    Radiators have 1/2" risers that run in wall so I can't change them.

    All zones re-piped with 1/2" PEX in a series loop.

    First floor radiators call for about 40,000 BTUs while the 2nd floor is about 15,000 BTUs. Note: I calculated based on an old EDR chart I found from the 40's.

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    Plumbing Contractor for 49 years johnjh2o1's Avatar
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    You can not run cast iron radiators on a series loop. Are you saying he piped it all in 1/2" ? If so this guy has no idea what he is doing. At this point the best thing to do is re pipe it with a one pipe system and monoflow tees.

    John

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    DIY Junior Member jasonnewyork's Avatar
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    John - you are correct, he piped each floor in series loops with 1/2" PEX.

    My original system was not monoflow, I had two separate pipes that snaked around the basement and one end of radiators connected to each of the 2 pipes. You suggest that I re-plumb with Monoflow tees? I guess I'm commited to cooper instead of PEX due to it's smaller inside walls?

    If I go with a monoflow setup, will I need to increase my main pipe size? The original 2 pipe setup used 1" pipes, I notice my sister-in-law's house has a 1-1/4" main with monoflow (her house is about 10 years newer). I plan to add a new zone with baseboards for the basement so need about 55k btu for 1st and 2nd floors.

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    Plumbing Contractor for 49 years johnjh2o1's Avatar
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    It sounds like your house is a 38' x 24' cape. A 1" main should be large enough. That is if you have two mains , one for each zone. If you will be heating your basement on a new zone that can be copper fin baseboard using PEX pipe. But i would use 3\4 not 1\2 inch.

    John

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    DIY Junior Member jasonnewyork's Avatar
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    John - I'm thinking maybe best to go with one zone for the first and second floors (like it was) and add a separate zone for the basement since I will be using baseboards.

    I have an appointment with a another plumber (licensed and in biz for 30 yrs) this Saturday. I'm going to disucss this with him.

    To be honest, I'm having a hard time finding anyone willing to take on this job. I guess all the plumbers form the 40's aren't in business anymore . I have a copy the B&G Zoning Guide book and have been reading it for the last two weeks. If I can't find a plumber, I might take this on myself.

    I have another question for you. I understand I need one monoflow tee for each radiator above the main installed on the return side. My radiators vary in size from 4000-9000 BTUs. Should I install 2 tees for the larger ones? Is there a simple way to calculate this? Or will one mono tee on return spaced equal distance from the supply side be enough? I know I cannot space the tees next to each other or the pressure drop will not be enough for the water to flow into the radiator.

    Thanks for all your help.

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    Plumbing Contractor for 49 years johnjh2o1's Avatar
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    If your going to put the house on one zone then the main needs to be 1 1/4.
    Also if it was on one zone prior to the re pipe and had two mains then it was a two pipe system with out monoflow tees. The one pipe system is the way to go using the existing radiators. As far as the monoflow tees one for all radiators above the main and two for any below the main. As far as spacing on the tees do not put two monoflow tees within 12" of each other or within 12" of a elbow in the main. Bye the way I'm not from the 40's but some times I feel that way.

    John

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    DIY Junior Member jasonnewyork's Avatar
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    The system originally a two pipe system with a 1" supply and 1" return feeding the entire house - basement, first floor, and second floor.

    I was leaning towards your recommendation of switching to a single, monoflow setup since it works and is easier to install.

    My plan is to restore the first and second floors to a single zone with a monoflow system using a 1-1/4" main. I will then add a second zone using 3/4" piping in series connected to baseboards.

    I always find it amazing how old knowledge is never transferred to newer generations. I'm learing by reading old documentation form the 40's but would be nice to have someone help me who has the expierence. Any chance you can do work in NY ?

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    Plumbing Contractor for 49 years johnjh2o1's Avatar
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    It sounds like your on the right track. As far as working in your area, my first 35 years in the business was in your area but the last 15 have been in Florida. It's been that long since I have worked on heating systems.

    John

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    DIY Junior Member jasonnewyork's Avatar
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    John - I have one more question, BTW: thanks for all your help.

    I was looking at my boiler last night, a Weil McClain 110K/88K BTU boiler. The return and supply pipes are 1". According to the manufacturer, the boiler input and output pipes are 1-1/4" but they recommend using 1" pipes, as I have now.

    It is my understand that I cannot use a 1-1/4" main (monoflow) because there will be a bottleneck as the water flows in and out of the boiler. I'm also confused how to plumb the basement loop as it will be at minimum a 3/4" system. Furthermore, the previous plumber installed zone valves along side the existing circulator pump. The largest zone valve available is 1".

    How does this configuration sound?

    1" pipe off supply side of boiler feeding a 1" manifold for 2 zone valves.

    1' supply and return lines controlled by 1" zone valve servicing the 1st and 2nd floors. This will be a 2 pipe system, as originally installed with standard tees on the supply and return sides

    3/4" piping with 3/4" zone valve servicing the basement baseborad radiators in a series loop.

    or,

    Switch everyting out and go with 1-1/4" main (against Weil McClain's recommendations) feed the 1st and 2nd floors in a monoflow (single pipe) system using the existing circulatar.

    Since there are no 1-1/4" zone valves, would need to add a second cirulator for a 3/4" loop to feed the basement baseboards.

    Note: either configuration will cause "traffic jams" as the sum of the two zone pipes is greater than the size of the boiler pipes.

    What do you think about this?

    Thanks again!

  11. #11
    Plumbing Contractor for 49 years johnjh2o1's Avatar
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    I would go with the 1-1/4 one pipe main and a second circulator for the basement zone. If you were to look inside of a 1-1/4 monoflow tee you would see how restricted it is, the opening in the 1" pipe will be much less restrictive.

    John
    Last edited by johnjh2o1; 11-05-2009 at 08:21 AM.

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    Moderator & Master Plumber hj's Avatar
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    Default heat

    You CANNOT use a loop system for cast iron radiators, and you DEFINITELY CANNOT use 1/2 PEX even if they would work in a loop. You had a plumber revise it, but NOT a plumber who knew even the basics of a heating system.

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    DIY Junior Member jasonnewyork's Avatar
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    Yes HJ, the plumber I hired know nothing about heating systems. My goal here is to restore and bring back to what it should be. After reading the posts on this forum, and information I gathered on other sites, I now know you cannot series loop cast iron rads.

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    DIY Junior Member jasonnewyork's Avatar
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    I had a licensed plumber come out this Saturday and look at my system. He too, like the rest of you, agreed that the previous plumber completely strewed up. He seemed highly knowledgeable and was recommended and used by a general contractor.

    Here are his recommendations (waiting for estimates for both)

    Option 1 (more expensive) - restore two pipe supply/return system as originally installed. He will use 1" copper mains (x2) with 1/2" copper tees to the radiators. I will have 2 heating zones, 1st and 2nd on zone 1 and basement on zone 2, one cirulator pump and 2 zone valves. He suggested I replace the baseboard in the 2nd floor bedroom with a cast iron radiator for more heat, that room was cold last winter.

    Option 2 (less expensive due to recycling materials) - install a manifold system in the boiler room. Homerun every radiator to the manifolds. Keep existing 3 zones. Install separate manifolds for the 1st and 2nd floor. Basement will be zoned and piped in series with baseboards. He thinks this will be cheaper because less soldering and can recycle a lot of the existing system. My issue will be 22 pipes coming into the manifolds. I plan to finished this basement and do not want a spagetti ceiling with pipes everywhere.

    He didn't seem to like the monoflow idea. I don't know why, he just said the 2 pipe setup is much better. I'm also worried becuase the recommend piping for my boiler is 1". It has 1-1/4" fittings but Weil recommends 1" piping. If I go monoflow, will need to go beyond manufacturer's recommendation, is this a bad idea?

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    Plumbing Contractor for 49 years johnjh2o1's Avatar
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    Quote Originally Posted by jasonnewyork View Post
    I had a licensed plumber come out this Saturday and look at my system. He too, like the rest of you, agreed that the previous plumber completely strewed up. He seemed highly knowledgeable and was recommended and used by a general contractor.

    Here are his recommendations (waiting for estimates for both)

    Option 1 (more expensive) - restore two pipe supply/return system as originally installed. He will use 1" copper mains (x2) with 1/2" copper tees to the radiators. I will have 2 heating zones, 1st and 2nd on zone 1 and basement on zone 2, one cirulator pump and 2 zone valves. He suggested I replace the baseboard in the 2nd floor bedroom with a cast iron radiator for more heat, that room was cold last winter.

    Option 2 (less expensive due to recycling materials) - install a manifold system in the boiler room. Homerun every radiator to the manifolds. Keep existing 3 zones. Install separate manifolds for the 1st and 2nd floor. Basement will be zoned and piped in series with baseboards. He thinks this will be cheaper because less soldering and can recycle a lot of the existing system. My issue will be 22 pipes coming into the manifolds. I plan to finished this basement and do not want a spagetti ceiling with pipes everywhere.

    He didn't seem to like the monoflow idea. I don't know why, he just said the 2 pipe setup is much better. I'm also worried becuase the recommend piping for my boiler is 1". It has 1-1/4" fittings but Weil recommends 1" piping. If I go monoflow, will need to go beyond manufacturer's recommendation, is this a bad idea?
    Jason if you go with a two pipe system there is a 2nd way to pipe it. It's called a two pipe reverse return. The cost should be the same but you get a much better balanced system. Instead of running the feed and return mains in the same direction from the boiler you run them in opposite directions from the boiler. What this dose is make the first radiator to feed the last one to return, thus balancing the system much better.The piping and the labor should be the same as should be the cost. As far as running home runs to a manifold it seems to me that you would need some way to balance the system as the furthest radiator would be heating much later then the first.

    John

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