Page 1 of 2 12 LastLast
Results 1 to 13 of 26
  1. #1
    Join Date
    Oct 2007
    Posts
    12

    Weil Mclain WGO oil boiler

    Is a Weil Mclain WGO boiler a cold start boiler? What is the difference between a cold start boiler and a condensing boiler? I called weil Mclain and they stated the the WGO is a cold start boiler but that you cannot install an outdoor reset because of condensation. But if it is a cold start boiler the temperature of the boiler could go to room temperture and wouldn't you get condensation. Can anyone please explain?

  2. #2
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    34,617
    A condensing boiler is one MEANT to condense flue gases and drop down to around 100 before exhausting usually with PVC or other plastic pipe. They would have a drain system to get rid of this water. Often a stainless steel heat exchanger.

    Yes, there can be some times of condensation when a cold start boiler first starts to come up to temp but that doesn't last long. I believe it is recommend to keep return to 140 or above. That doesn't leave much room to drop the temp setting.

    Condensing boilers are most efficient with cool water such as radiant floor and lose efficiency when they have to run hot for baseboard.

  3. #3
    Join Date
    Oct 2007
    Posts
    12

    Weil Mclain Gold WGO

    Thank you for your quick response. But is the WGO a cold start boiler and how low would the temp drop on a cold start? I was told that these new boilers are so tight that with a high temp limit of 180 they rarely get below 105. Please advice.

  4. #4
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    34,617
    It is cold start the way it comes. It will drop to room temp if off long enough. During most of the winter, it will cycle enough to stay rather warm. How much depends upon sizing. Too many oversize boilers which means frequent cycles and lower efficiency.

  5. #5
    Join Date
    Oct 2007
    Posts
    12

    Weil Mclain Boiler

    Thanks for the information. I have one more question. I have a WTGO gold with the tankless coiler. I also have a boilermate indirect water heater. I got the WTGO as a back up in case the boilermate died. The boiler came with a Honeywell L7224A aquastat and on this particular model you cannot shut off the low limit (therefore not creating a cold start). I can only lower it to 110. Is there anyway to wire this aquastat for a true cold start? Also, I have read that these boilers are so tight even with cold start they rarely go below 100 degrees anyway so am I Ok with a 110 degree low limit? I am still going to save fuel compared to a tankless coil startup, correct?

  6. #6
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    34,617
    With the tankless coil, your WGO would not be configured as a cold start boiler. At a glance that control looks like it won't switch to a cold start configuration. At this point, I better wait until a boiler man sees this and goes further. I've never worked on a boiler with this new control and a tankless. The last WGO we did had no tankless and had the old mechanical aquastat. I would think it still would be wise to use the indirect rather than the tankless!

    Hello Noel!

  7. #7
    Join Date
    Oct 2007
    Posts
    12

    You are correct

    You are correct my friend, it is not meant to be wired cold start even though I am running an Argo 3 zone relay which has a cold start option which I am using. I have been asking around today and most say that with a low limit set at 110 I am still saving fuel and will not harm the boiler with condensation issues. Would love to hear from anyone else with what they think.

    Thanks
    Mark

  8. #8
    Join Date
    Jan 2002
    Location
    New Hampshire
    Posts
    1,285

    You're correct

    Honeywell has made a few versions of that aquastat, and the less expensive one has very few field adjustable options, such as shutting off the low limit.

    Guess which one they sell to boiler manufacturers, since they sell an add-on package that plugs into the control to give you more options?

    You'll be fine with the low limit set low. Just turn off the boiler when you go away on vacation in warm weather.

    Noel

  9. #9
    Join Date
    Oct 2007
    Posts
    12

    Cold Start

    Noil, Thanks for the info do you know which honeywell add on that I can buy if I wanted to? I called Honeywell today and spoke to a very nice gentleman but all he could suggest was to buy the L7224U which is the cousin to the one that is on my boiler (L7224A). But as you stated as long as I do not harm the boiler with condensation issues with a low limit setting of 110 I might just leave it alone. What do you think?

  10. #10
    Join Date
    Jan 2002
    Location
    New Hampshire
    Posts
    1,285
    I'd leave it alone.

    The warmer boiler will stay cleaner, cost less to maintain, and probably last longer.

    It's a, "Pay me now, or pay me later" type of situation.

    Noel

  11. #11
    Join Date
    Oct 2007
    Posts
    12

    You are right

    Noel, You are right, I do not want to be penny wise and pound foolish. As long as I am not keeping the boiler at 160 degrees I can live with the extra fuel to keep it at 110 degress. I am still confused how condensation will not form at this low temp considering the fact that the boiler will probably not get to the high limit setting of 180 degrees in the summer. Please advice.
    Thanks

  12. #12
    Join Date
    Jan 2002
    Location
    New Hampshire
    Posts
    1,285

    It will slightly condense

    The key with a cold start boiler is to have it come up beyond the condensing temperature range during the run cycle. As long as it doesn't condense for a prolonged period (cast iron radiators; radiant slabs), it will only wet a little and dry itself out as the return passes the 125-130 range.

    The Euro boilers actually have channels in them, between the sections, to guide this moisture back into the fire for re-evaporation.

    Fear not, if your supply water temp comes up steadily.

    Noel

  13. #13
    Join Date
    Jun 2003
    Location
    New Hampshire
    Posts
    2,666
    You don't have any cast iron radiators do you?

Page 1 of 2 12 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Comfortech Show Promo Image

Related Forums

Plumbing Talks | Contractor Magazine
Forums | Electrical Construction & Maintenance (EC&M) Magazine
Comfortech365 Virtual Event