+ Reply to Thread
Page 3 of 4 FirstFirst 1234 LastLast
Results 21 to 30 of 31
  1. #21
    Join Date
    Aug 2009
    Location
    Massachusetts
    Posts
    50

    Default Re: forced hot water heat question







  2. #22
    Join Date
    Feb 2008
    Posts
    554

    Default Re: forced hot water heat question

    Frank:

    Thanks for the photos--the unit in question turns out to be a Honeywell R8845U switching relay.

    According to the Honeywell website it contains 2 replaceable socketed 120 v relays, and a replaceable 1 amp transformer fuse.

    The Honeywell site has some literature on the unit at the site below---when you get to the site go to the lower right hand corner & enter the unit model number (R8845u) and the type of document you want to view in the appropriate spaces---I wasn't able to open the pdf documents on my system.


    The basic operation of this switching system is that when the t-stat (which is a switch) closes, it shorts out the 2 t-stat wires that go to the transformer in the unit---the 24v in the t-stat circuit causes an electromagnetic force in the xformer that "pulls in" the metal contacts of the relay and causes 120V to energize the circulator---at the same time the main aquastat is activated and the burner is ignited--the boiler will continue to heat until the t-stat is "satisfied" & opens, shutting down the boiler.

    Make sure you turn off the power switch before poking around inside the switching unit.

    Check the contacts of the relay---they often crud up--take a piece of emery cloth or thin fingernail file & clean the contacts.

    Check the fuse for continuity; you can check the operation of the circulator by temporarily disconnecting the 2 wires that lead from the circ to the unit & attach a lamp cord that has been stripped of insulation at the end to the 2 wires of the circ---wrap tape or wire nuts on the temporary connections to prevent an accidental short--- plug it into a 120v receptacle.

    You should hear the pump working if it is good---many of these pumps run quietly, so take a large screwdriver & hold the metal part to the housing of the pump & place the plastic part to your ear---you should hear a high-pitched whining if the pump is running---any length of wood, or even a hammer can be likewise used in this test.

    If the pump is good, it points to a bad relay for the 2nd floor.

    According to Honeywell, you can switch the plug-in relays---try this---if the upstairs heat now works, & the 1st floor doesn't, then you know it's the relay.

    http://customer.honeywell.com
    Last edited by NashuaTech; 10-21-2009 at 08:10 PM.

  3. #23
    Join Date
    Feb 2009
    Posts
    693

    Default Re: forced hot water heat question

    NT is the most imformative member who was ever on this site. God bless you.

  4. #24
    Join Date
    Aug 2009
    Location
    Massachusetts
    Posts
    50

    Default Re: forced hot water heat question

    Thank you very much for your help. I will try your suggestions.
    I made a few calls, and was unable to locate the replaceable relays. I was able to locate the whole unit locally.
    Couple of questions,
    Does it use both of those relays to control the upstairs heat?
    Does the box below the R8845U perform the same function, but just a different "model"?
    Could there be a switch anywhere that I am missing? They repaired a leak just above the green pump before I moved in. I wonder if they did something?
    Hopefully I will have heat upstairs before it gets too cold! Luckily it's been unseasonably warm lately.
    Thanks again!

  5. #25
    Join Date
    Feb 2008
    Posts
    554

    Default Re: forced hot water heat question

    Frank:

    Go thru the test procedures mentioned before you buy anything---according to the mfgr, the R8845U contains both relays for the upstairs & downstairs zones.

    Clean the contacts on the malfunctioning relay with emery cloth to see if you can bring it back to life---turn up the 2nd floor t-stat & use a popsicle stick, or small piece of wood to manually close the spring-loaded contacts on the dead relay to see if it fires the boiler.

    Can't see the unit below the R8845 you mention---if it has any model numbers on it, please post.

    Check the circulator for good operation using the lamp cord.
    Last edited by NashuaTech; 10-22-2009 at 09:19 AM.

  6. #26
    Join Date
    Aug 2009
    Location
    Massachusetts
    Posts
    50

    Default Re: forced hot water heat question

    I will do all of that this weekend, haven't had much time this week. And fortunately, it's been very warm.
    In the 4th picture, it shows the R8845U with the cover off, and below it is another box, on the inside it says "Triple aquastat -relay type l8124a,c l8151a". On the outside it says Honeywell. Is an aquastat a totally different unit?

  7. #27
    Join Date
    Feb 2008
    Posts
    554

    Default Re: forced hot water heat question

    Frank:

    The aquastat ("aqua"-water, "stat"-status) is like the "main switchboard" of the boiler system---its main job is to keep track & regulate the boiler water temp so it doesn't get to high or too low---in YOUR case you have a L8124C "triple aquastat", which also regulates the domestic hot water supply as well.

    The aquastat has a little bulb that goes directly into the boiler to constantly sense water temp & can shut down the burner as a safety device if the temp gets too high.

    Many wiring schemes set up circ zone 1 to run off the L8124 and zone 2 to run off the R8845U.

  8. #28
    Join Date
    Aug 2009
    Location
    Massachusetts
    Posts
    50

    Default Re: forced hot water heat question

    "Many wiring schemes set up circ zone 1 to run off the L8124 and zone 2 to run off the R8845U. "
    I think that's how mine works.
    So far, the only thing I have tried this weekend was pulling out the relays, cleaning the contacts, and changing their positions, and still doesn't work. The relay light doesn't come on. When I press the test button, the boiler does kick on, but no circulator.

  9. #29
    Join Date
    Aug 2009
    Location
    Massachusetts
    Posts
    50

    Default Re: forced hot water heat question

    Ok, so I am sure the circulator is toast. I had an extension cord that was a victim of a hedge trimmer accident, and I wired it directly to the circulator, and it did nothing. Completely silent. I got the meter and verified that I had power going to the circulator. I think I may have also made a dumb mistake. When it didn't work, I had the foolish idea of reversing the wires. I plugged it in and heard a zzzt zzzt noise. I bet i fried the capacitor! Now, I know that I can get the cartridge, and replace that, but will it work, since I have probably fried the capacitor?
    Also, the fact that the "relay" led on the R8845U does not light up bothers me. I wonder if I also need a relay? Could the bad motor burn the relay too?
    I kinda think the home inspector should have caught this. Now it's going to cost me money. At least I am learning something.
    Last edited by frankjc; 10-25-2009 at 01:09 PM.

  10. #30
    Join Date
    Aug 2009
    Location
    Massachusetts
    Posts
    50

    Default Re: forced hot water heat question

    Update. Still not fixed, I have had too many things going on lately, car trouble, etc. At this point, I am thinking I need a relay and a circulator. I can figure out how it's wired when I get home, and post it. The fact that I get no power at the wires that go to the pump make me think I need a relay, and the fact that the pump doesn't come on when wired directly to the wall outlet lead me to believe the pump is dead.
    The local supplier stocks the R8844U relay for $55, and the Taco 007-f5 circulator for $95.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •