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Low return water temp protection methods

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Erin3
Erin3 Member Posts: 11
in THE MAIN WALL

I dont really know how to properly ask this question - but what other equivalent methods are there to protect a cast iron boiler from low return temps? I’m on my 3rd contractor, getting a 2nd quote for a boiler replacement and it seems like none of them have ever heard of needing/wanting this before. And US Boiler makes it wonderfully easy for me to ask them to add their bypass kit to the quote, except that the kit is apparently out of stock or hard to get?

I’ve seen a few photos on here where you use thermostatic mixing valves instead of a speed controlled pump. That seems okay to me to.

To put it more succinctly, what the heck do I ask these guys to use if the kit I want is not available?

IMG_1894.png

And just for laughs here was his response to me asking for the bypass kit and a magnetic separator:

IMG_1895.jpeg

Thanks

Comments

  • HydronicMike
    HydronicMike Member Posts: 359

    Where are you located? You need someone who understands hydronics, and can read a manual. Boiler protection is fairly easy, and can be done a number of ways.

    Erin3
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 20,327

    The second picture is the better method. If the kit is unavailable, you can buy your own circ and sensor the rest is just standard pipe and fittings.

    Most HW jobs with baseboard come up to temp quickly and don't require protection but there are always exceptions. If you have and older system with CI radiators or a gravity conversion job that holds a lot of water, then you may need protection

    Erin3
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 12,399

    I have a question for @Erin3. What type of radiators are you connecting the replacement boiler to?

    If you have a 1940s-era or older home with a large water-content cast-iron radiator system, you need to think about boiler protection. If you have a Monoflo single-pipe system with the wall convectors that were popular in the 1950s, you may not need boiler protection. If your home is equipped with fin-tube baseboard radiators, you definitely do not need boiler protection.

    I can explain why if you need me to, but it is easier to tell us what type of radiators you have before we get into a lengthy discussion on the topic.

    This is an unusually short answer from me… go figure.

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

    Erin3
  • hot_rod
    hot_rod Member Posts: 27,631

    the type and number of heat emitters compared to the boiler output?

    Light weight low mass copper fintube or fan coils should not need boiler return protection , for example

    Large iron radiators , larger steel piping may however

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    EdTheHeaterManErin3
  • Erin3
    Erin3 Member Posts: 11

    House was built in 1910, we have large (3” or 4” OD) iron pipes in the basement that branch off to smaller iron pipes to feed the radiators. There’s also an old steel expansion tank leftover from who knows when in the ceiling between the floor joists. Based on what I’ve read here, I believe it is an old gravity conversion.

    We currently have a Triangle Tube Prestige Excellence 110 combi that has had quite a few issues and has left us without heat and hot water numerous times, which is why I’m going with a separate direct power vented water heater and cast iron boiler.

    It’s about a 1800 sq ft house and my own heat loss study came out around 105k - 115k, depending on infiltration. My count of the radiators heat output was between 72k - 78k, depending on which EDR/s I used for a few of the more unique radiators we have.

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