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system upgrade design for radiant and DHW

wolfcry911wolfcry911 Member Posts: 1
edited January 4 in THE MAIN WALL
edit// I apologize, I was trying to post this in Main Wall

I'm looking for ideas on how to best approach my heating and DHW.

Background: I live in the NE in a ranch built in 1954 with forced hot water heat from an old (original?) US Radiator Corp oil boiler with a newer Beckett burner feeding a monoflo loop. DHW is from a coil off the boiler. Everything currently works fine, aside from using more oil than I'd like. Side note: A tech once told me never to replace the boiler - he said it isn't the most efficient, but will last forever (old cast iron).

Ok, so there's a 1978 320 sq. ft. addition on the house, which when I purchased the house 8 years ago had baseboard radiators that were fed from the monoflo T that had fed a radiator removed for the addition. I've since remodeled that addition and have eliminated the heat in the room (kitchen) altogether. The former supply and return to the monoflo loop were capped off (and eventually connected to one another to reduce restriction in the system). The room is well insulated with 3" closed cell spray foam walls and rafters and an additional 5" open cell on rafters. There has been no heat for 3 years and while it is noticeably colder than the rest of the house, it's not unbearable. My idea all along has been to use under floor radiant heating for this room. I'll probably use 2 250' loops of 1/2" pex in thermofin C transfer plates.

In addition to needing to feed the radiant system, I'd like to change the DHW system so as to not need to burn oil in the summer. I have in my possession an electric GE hot water tank never used (about 5 years old now, so there's no returning it now). The main bath and kitchen faucet are approximately 30+ feet from the boiler, so I'm wasting water to get it hot as well.

Using what I have (don't wish to upgrade boiler, or purchase an indirect tank, and no gas in the street), what are my options to feed the radiant system and DHW?

I was originally going to have house DHW from hot water tank only, eliminating the coil, and supplying the radiant system with another zone off the boiler into a Taco RMB-1. But now I'm wondering if an open system for DHW and radiant system is better, or even a closed system off the hot water tank using something like the Taco XPB. Then, I had the thought of supplying the radiant system from the coil, without the need of a second zone and only used in the winter when the boiler is running anyway. I was also wondering about the feasibility or efficiency of running the hot water tank in series with the coil?

Thanks in advance for any input!


  • atlas40atlas40 Member Posts: 4
    On the heating side what size is mono flow pipe size (is it the Same size) if main flow pipe is 1 or 1 1/4 and rad was 3/4 to baseboards reconnecting feed and return is still a restriction cut out and joint pipe straight thru as far as kitchen cut out sink base floor and install toe kick heater to heat kitchen and cover with new sink base floor panel Removable if big room, put 2 kicks.
    Pipe electric tank as a storage tank off coil with recirc pump
    006 bronze use taco multi zone box with priority zone for hot water tank.
    I repiped my old cast iron feed and return system keep all existing rads with 1” mono flow copper pipe, I put mono t’s on return side as to slow flow through rads. And space feed and return t ‘s 16” apart.
    If your mono flow System is feeding baseboards in rooms it will not work. Cut in ball valves under baseboards as quick fix and close valves with bleeder t at boiler. Open valves when u need to drain system. Please send me more info if I got something misunderstood. Thank you. Eric Haywood
  • atlas40atlas40 Member Posts: 4
    Also I forgot to ask if someone installed a high out circ pump
    Like taco 0010 Thanks again. Eric
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