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tankless coil heat only

I have a weil mclain eg50 gas fed steam boiler Feeding most of the home.  I already have 1 hot water zone, going to a single room on the first floor, coming off the bottom of the boiler and it works fine. I want to add baseboard hot water heat to my basement(same floor as boiler).  My boiler is capable of accepting the tankless coil.  My questions are

1. can I add the next zone off the same place(bottom of the boiler)? With two seperate ciculators and a second thermostat.

2. Will that take to much water out of the boiler if both zones were operating at the same time leading to possible damage?

3. would it be best to go the tankless coil route?

4.  I will have to run the piping up to ceiling of basement and back down to baseboards to keep them out of the way. Would this be a problem?

Thanks for any help you can offer.


  • Paul48Paul48 Member Posts: 4,492

    You should run the hydronic zones off a flat plate heat exchanger.
  • bundlebundle Member Posts: 5
    flat plate v coil

    i never heard of the flat plate heat exchanger. I checked it out and it looks like a good idea. hOW DOES THAT ATTACH TO MY EG-50 BOILER? does it go into the same place as the coil? 
  • Paul48Paul48 Member Posts: 4,492

    It's a much better alternative for running  hydronic off a steam boiler. If your first floor zone develops a leak now,you'll flood the boiler.Use the pump from that zone to feed the heat exchanger, and forming one loop.Then run your zones on the other side of the heat exchanger.This isolates the boiler from the hydronic system and allows for auto-fill/regulation on the hydronic side. That allows for the system to be under pressure and helps eliminate problems with air.You add the auto-fill /regulator, expansion tank, and spirovent or another means of air elimination and you're done.
  • bundlebundle Member Posts: 5
    flat plate exchanger

    So the hot water from the bottom of the boiler goes in one side of the fphe. it then goes directly back to the boiler. now i take my old zone and the new one and run them through other side of the fphe. and have two zone valves, circulators and thermostats.  The water from boiler and the heat zones never meet. correct. also add expansion tank and spiro vent.   am i close?
  • Paul48Paul48 Member Posts: 4,492

    Single circulator and 2 zone valves. Hopefully someone will post some pictures for you.
  • Danny ScullyDanny Scully Member Posts: 1,228
    I wouldn't

    I wouldn't use a flat plate heat exchanger for a means of condensate hot water heating. Any system designed like this I have ever seen had issues. Flat plate heat exchangers used in condensate hot water heating applications are almost always prone to clogging. Unless you're prepared to install a quality strainer and frequently flush out the flat plate heat exchanger, I wouldn't install it. I would, however, recommend an internal coil as you mentioned or a external Everhot solid copper shell heat exchanger or any shell and tube heat exchanger.
  • Paul48Paul48 Member Posts: 4,492
  • bundlebundle Member Posts: 5
    auto fill

    My auto fill is on my cold water supply. Is there an issue with the cold water entering a fully heated boiler. If it opens while boiler it at operating temp? Can I also just take the new zone off the bottom of boiler same an first zone? The first zone is only one room, maybe a 40 foot run. New zone would be half of basement. Maybe 60 ft run.
  • Paul48Paul48 Member Posts: 4,492

    Read the article, it answers your questions.Look at the diagram.....if you use a heat exchanger, you create a completely independent loop. The water in that loop is just heated by the boiler water. The addition of auto-fill, expansion tank and air removal in that loop have nothing to do with the boiler.Once again, you can do it without a heat exchanger, and that is also addressed in the article. One hundred feet of 3/4" copper fin-tube is roughly 50000 btus.
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