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Boiler upgrade

Hi,

I live in the NE. I just moved into an old house built around 1950. The house has a tankless gas water boiler for heating and domestic hot water. Boiler is old Burnham holiday of over 50 years old with 150,000 BTU input and 120,000 output. House has 2 floors with around 1,800 square ft and has very poor insulation We have two zone heat : one per floor. I have 2 questions:

1- the water in the shower gets freezing when the hot or cold water is used elsewhere in the house. We can't use washing machines, dishwasher or even wash our hands without making the other person freeze in the shower. What is the problem and what could be the solution?

2- I would like to retrofit this old boiler and I'm looking into going with more efficient gas boilers or maybe mod con boiler. Currently I have baseboard heat with 180 degrees water supply. I've been reading a lot about how mod con works best with lower water temperature. I'm afraid if I go with mod con and lower the temp of the water supply in the baseboard I will not get enough heat as quick  as I'm used to it and will sacrifice the comfort in the house which for me is the main priority for heating. I have done a heat loss on my own and found out that my heat loss is 45,000 BTU. I have measured my exisitng baseboard length and I have 100 linear ft for the entire house which I believe (based on some info I found online of 550btu/lf/hr per baseboard) I should be just about right and I'm not over sized (55,000 BTU). My question should I go with high efficiency mod con or mid range effciency with cast iron heat exchanger. 

I would appreciate if someone can honestly answer this.

Thank you

Comments

  • Steve Whitbeck
    Steve Whitbeck Member Posts: 669
    Mod CON

     If you go with a mod con install the outdoor temp sensor and the boiler if set up properly will supply the water temperature that you will need to keep the house comfortable. I like the Lochinvar WHN model.
  • Andrea2013
    Andrea2013 Member Posts: 4
    Mod con

    Thank you Steve,

    I read conflicting views about using mod con with old exisitng baseboard. Some say it will work and some say it will not work and the temperature will stay cold in the baseboard.
  • Andrea2013
    Andrea2013 Member Posts: 4
    Mod con

    Thank you Steve,

    I read conflicting views about using mod con with old exisitng baseboard. Some say it will work and some say it will not work and the temperature will stay cold in the baseboard.
  • pipeking
    pipeking Member Posts: 252
    if it gets freazing cold

    then it very well may not be your boiler, i would look at the shower valve first. 1) how old is it, 2) does your shower valve have thermostatic mixing, 3) do u have a thermostatic mixing valve at the tankless,4) have these failed?

    now of corse upgrading your hot water supply will give u more hot water, but runing out of hot water is differant then the hot water getting redirected.       running out: the hot water gradually gets cold. 

    redirecting hot water: happens when thermostatic mixing valves r not used and when anther fixture is turned on it takes the hot water from another, which causes instant temp change.                                                
  • SWEI
    SWEI Member Posts: 7,356
    mod/con with baseboard

    Will work just great - once you adjust the reset curve properly your thermostat becomes a high limit control and should not shut the boiler off unless you have heat gain from some other source (wood stove, solar gain, etc.)  Consider using a smart circulator, which will reduce the electrical consumption by about 75% over a conventional circulator.



    Proper sizing of an indirect DHW heater will cure the cold shower problem.
  • Jason_13
    Jason_13 Member Posts: 299
    Either or

    Either ones will give you a good operation at minimal fuel cost

    Either one you decide on use ODR and sidewall vent. There are some lower return temp cast iron boilers on the market that will get the operational cost closer between the two products. Most fuel savings are set up by proper sizing and system efficiency.
  • Charlie from wmass
    Charlie from wmass Member Posts: 4,216
    as time has passed I have found ModCon boilers

    work very well on any system they are used with. This is as long as they are maintained and they are sized and installed properly. If your heat loss is 45kbtu and your baseboard is rated 55kbtu then you are a good candidate for a mod con boiler.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
    https://heatinghelp.com/find-a-contractor/detail/charles-garrity-plumbing-and-heating
  • Eastman
    Eastman Member Posts: 927
    Andrea

    What are your fuel bills?
This discussion has been closed.