PTAC hydronic unit

Hi all, Hopefully I can get some knowledge to avoid shoveling money on unskilled people tying to fix my PTACs. One guy came today and the explanations he gave to me were contradictory at best… I have several PTAC units (McQuay Incremental) with Hydronic heat section. It’s water based. Today my concern is heat. I have a few question that may seem stupid but I’m not exactly the smartest 🙂 1 – Will the heat work without power? My assumption is yes as it seems that the unit is taking the heat from the hot water of the building and that there is not pump in the unit. Of course, I won’t be able to put the fan on to blow hot air, but the coil should at least be warm right? 2 – What is the purpose of the automatic valve? (or zone valve). There is controller on top of it and some of my units don’t have it and work just fine. Finally, last question specific to one of my units. When I bleed it, the return pipe gets extremely hot but not heat goes into the coil. I suspect the pipe to be obstructed but how is it possible that the hot water comes from the return pipe? (the supply pipe, the one with the auto-valve, remains dead cold). All valves are open, both return and supply. Thank you for any help, I must say I’m a bit desperate with these units and building management keeps on sanding waves after waves of unskilled (probably very cheap) people to fix them.

grandsteph

in Plumbers and Plumbing 11 years and 5 months ago

7

Please log in, in order to post replies!

7 replies

Newest Oldest

grandsteph | 10 years and 11 months ago

string(1) "1"
object(WP_User)#5146 (8) {
  ["data"]=>
  object(stdClass)#4930 (12) {
    ["ID"]=>
    string(6) "180922"
    ["user_login"]=>
    string(10) "grandsteph"
    ["user_pass"]=>
    string(34) "$P$BO60aD9Wh87J3WdpxbQkC3JR/C5J1Y0"
    ["user_nicename"]=>
    string(10) "grandsteph"
    ["user_email"]=>
    string(17) "giloppe@yahoo.com"
    ["user_url"]=>
    string(33) "http://www.giloppephotography.com"
    ["user_registered"]=>
    string(19) "2017-08-10 13:43:20"
    ["user_activation_key"]=>
    string(0) ""
    ["user_status"]=>
    string(1) "0"
    ["display_name"]=>
    string(10) "grandsteph"
    ["spam"]=>
    string(1) "0"
    ["deleted"]=>
    string(1) "0"
  }
  ["ID"]=>
  int(180922)
  ["caps"]=>
  array(1) {
    ["bbp_participant"]=>
    bool(true)
  }
  ["cap_key"]=>
  string(15) "wp_capabilities"
  ["roles"]=>
  array(1) {
    [0]=>
    string(15) "bbp_participant"
  }
  ["allcaps"]=>
  array(1) {
    ["bbp_participant"]=>
    bool(true)
  }
  ["filter"]=>
  NULL
  ["site_id":"WP_User":private]=>
  int(1)
}

nope. Valves are just mounted on a pipe.

biggles | 11 years and 4 months ago

string(1) "1"
object(WP_User)#5145 (8) {
  ["data"]=>
  object(stdClass)#4912 (12) {
    ["ID"]=>
    string(5) "38241"
    ["user_login"]=>
    string(7) "biggles"
    ["user_pass"]=>
    string(34) "$P$B8pNfxbuPPgfU2BrlXUdx.j0F4G9cg0"
    ["user_nicename"]=>
    string(7) "biggles"
    ["user_email"]=>
    string(20) "vze1rdsv@verizon.net"
    ["user_url"]=>
    string(22) "/forums/users/biggles/"
    ["user_registered"]=>
    string(19) "2017-08-10 13:50:16"
    ["user_activation_key"]=>
    string(0) ""
    ["user_status"]=>
    string(1) "0"
    ["display_name"]=>
    string(7) "biggles"
    ["spam"]=>
    string(1) "0"
    ["deleted"]=>
    string(1) "0"
  }
  ["ID"]=>
  int(38241)
  ["caps"]=>
  array(2) {
    ["subscriber"]=>
    bool(true)
    ["bbp_participant"]=>
    bool(true)
  }
  ["cap_key"]=>
  string(15) "wp_capabilities"
  ["roles"]=>
  array(2) {
    [0]=>
    string(10) "subscriber"
    [1]=>
    string(15) "bbp_participant"
  }
  ["allcaps"]=>
  array(4) {
    ["read"]=>
    bool(true)
    ["level_0"]=>
    bool(true)
    ["subscriber"]=>
    bool(true)
    ["bbp_participant"]=>
    bool(true)
  }
  ["filter"]=>
  NULL
  ["site_id":"WP_User":private]=>
  int(1)
}

the building pumps can vary as all the units in the building call or close off.bleeding only makes the flow easier that is why you are feeling hot water with it not going to the actual return.using just the coil without electric is just an old fashion radiator if you have a manual swing arm there.don’t bother bleeding the building system does that.are the valves 3-way with 3 pipes into them?

eman134 | 11 years and 5 months ago

string(1) "1"
object(WP_User)#4930 (8) {
  ["data"]=>
  object(stdClass)#4938 (12) {
    ["ID"]=>
    string(6) "177006"
    ["user_login"]=>
    string(7) "eman134"
    ["user_pass"]=>
    string(34) "$P$BaRrlDjFBcYAeDJ9.lwOTJ9pQC9nsT."
    ["user_nicename"]=>
    string(7) "eman134"
    ["user_email"]=>
    string(23) "errol832000@hotmail.com"
    ["user_url"]=>
    string(29) "http:///forums/users/eman134/"
    ["user_registered"]=>
    string(19) "2017-08-10 14:25:55"
    ["user_activation_key"]=>
    string(0) ""
    ["user_status"]=>
    string(1) "0"
    ["display_name"]=>
    string(7) "eman134"
    ["spam"]=>
    string(1) "0"
    ["deleted"]=>
    string(1) "0"
  }
  ["ID"]=>
  int(177006)
  ["caps"]=>
  array(2) {
    ["subscriber"]=>
    bool(true)
    ["bbp_participant"]=>
    bool(true)
  }
  ["cap_key"]=>
  string(15) "wp_capabilities"
  ["roles"]=>
  array(2) {
    [0]=>
    string(10) "subscriber"
    [1]=>
    string(15) "bbp_participant"
  }
  ["allcaps"]=>
  array(4) {
    ["read"]=>
    bool(true)
    ["level_0"]=>
    bool(true)
    ["subscriber"]=>
    bool(true)
    ["bbp_participant"]=>
    bool(true)
  }
  ["filter"]=>
  NULL
  ["site_id":"WP_User":private]=>
  int(1)
}

is the zone valve on the unit opening? …if there is a manual hold open lever, set it to open and you should get circulation…sounds like a failed zone valve

Master Plvmber | 11 years and 5 months ago

string(1) "1"
object(WP_User)#5146 (8) {
  ["data"]=>
  object(stdClass)#5147 (12) {
    ["ID"]=>
    string(4) "1447"
    ["user_login"]=>
    string(14) "Master Plvmber"
    ["user_pass"]=>
    string(34) "$P$BSHLZQSJWUzjnaSv9fyWJpNYjwcz.u."
    ["user_nicename"]=>
    string(14) "Master Plvmber"
    ["user_email"]=>
    string(24) "info@gatewayplumbing.com"
    ["user_url"]=>
    string(30) "http://www.GatewayPlumbing.com"
    ["user_registered"]=>
    string(19) "2007-08-10 20:40:53"
    ["user_activation_key"]=>
    string(0) ""
    ["user_status"]=>
    string(1) "0"
    ["display_name"]=>
    string(14) "Master Plvmber"
    ["spam"]=>
    string(1) "0"
    ["deleted"]=>
    string(1) "0"
  }
  ["ID"]=>
  int(1447)
  ["caps"]=>
  array(2) {
    ["subscriber"]=>
    bool(true)
    ["bbp_participant"]=>
    bool(true)
  }
  ["cap_key"]=>
  string(15) "wp_capabilities"
  ["roles"]=>
  array(2) {
    [0]=>
    string(10) "subscriber"
    [1]=>
    string(15) "bbp_participant"
  }
  ["allcaps"]=>
  array(4) {
    ["read"]=>
    bool(true)
    ["level_0"]=>
    bool(true)
    ["subscriber"]=>
    bool(true)
    ["bbp_participant"]=>
    bool(true)
  }
  ["filter"]=>
  NULL
  ["site_id":"WP_User":private]=>
  int(1)
}

What makes you sure you’ve got the supply and return pipes identified properly? It doesn’t matter much to the coil, anyway.

grandsteph | 11 years and 5 months ago

string(1) "1"
object(WP_User)#5145 (8) {
  ["data"]=>
  object(stdClass)#5148 (12) {
    ["ID"]=>
    string(6) "180922"
    ["user_login"]=>
    string(10) "grandsteph"
    ["user_pass"]=>
    string(34) "$P$BO60aD9Wh87J3WdpxbQkC3JR/C5J1Y0"
    ["user_nicename"]=>
    string(10) "grandsteph"
    ["user_email"]=>
    string(17) "giloppe@yahoo.com"
    ["user_url"]=>
    string(33) "http://www.giloppephotography.com"
    ["user_registered"]=>
    string(19) "2017-08-10 13:43:20"
    ["user_activation_key"]=>
    string(0) ""
    ["user_status"]=>
    string(1) "0"
    ["display_name"]=>
    string(10) "grandsteph"
    ["spam"]=>
    string(1) "0"
    ["deleted"]=>
    string(1) "0"
  }
  ["ID"]=>
  int(180922)
  ["caps"]=>
  array(1) {
    ["bbp_participant"]=>
    bool(true)
  }
  ["cap_key"]=>
  string(15) "wp_capabilities"
  ["roles"]=>
  array(1) {
    [0]=>
    string(15) "bbp_participant"
  }
  ["allcaps"]=>
  array(1) {
    ["bbp_participant"]=>
    bool(true)
  }
  ["filter"]=>
  NULL
  ["site_id":"WP_User":private]=>
  int(1)
}

Well, following your lead, I actually tried several things. I ended up unplugging the coil from the return line. Then purged it by opening up the supply. Big nasty black juice went out. Replugged everything and … The pipes are getting warm but from the return line! I could feel both pipes and could definitely tell that the hot water is coming from the return line. And warm but not hot enough. Not much I can do now, I passed the info to the building management. Hopefully they’ll find a guy that can properly fix a pump because obviously we don’t get enough pressure and the pressure we get comes from the wrong end! I’d laugh about it if it wasn’t mine …

grandsteph | 11 years and 5 months ago

string(1) "1"
object(WP_User)#4930 (8) {
  ["data"]=>
  object(stdClass)#5149 (12) {
    ["ID"]=>
    string(6) "180922"
    ["user_login"]=>
    string(10) "grandsteph"
    ["user_pass"]=>
    string(34) "$P$BO60aD9Wh87J3WdpxbQkC3JR/C5J1Y0"
    ["user_nicename"]=>
    string(10) "grandsteph"
    ["user_email"]=>
    string(17) "giloppe@yahoo.com"
    ["user_url"]=>
    string(33) "http://www.giloppephotography.com"
    ["user_registered"]=>
    string(19) "2017-08-10 13:43:20"
    ["user_activation_key"]=>
    string(0) ""
    ["user_status"]=>
    string(1) "0"
    ["display_name"]=>
    string(10) "grandsteph"
    ["spam"]=>
    string(1) "0"
    ["deleted"]=>
    string(1) "0"
  }
  ["ID"]=>
  int(180922)
  ["caps"]=>
  array(1) {
    ["bbp_participant"]=>
    bool(true)
  }
  ["cap_key"]=>
  string(15) "wp_capabilities"
  ["roles"]=>
  array(1) {
    [0]=>
    string(15) "bbp_participant"
  }
  ["allcaps"]=>
  array(1) {
    ["bbp_participant"]=>
    bool(true)
  }
  ["filter"]=>
  NULL
  ["site_id":"WP_User":private]=>
  int(1)
}

Thank you Master Yoda, hum, plvmber 🙂 I will try that and let you know. I’m so happy so happy my instinct was right about the heat and lack of power! It looks like a good and honest PTAC repair team is hard to come by!

Master Plvmber | 11 years and 5 months ago

string(1) "1"
object(WP_User)#5148 (8) {
  ["data"]=>
  object(stdClass)#5146 (12) {
    ["ID"]=>
    string(4) "1447"
    ["user_login"]=>
    string(14) "Master Plvmber"
    ["user_pass"]=>
    string(34) "$P$BSHLZQSJWUzjnaSv9fyWJpNYjwcz.u."
    ["user_nicename"]=>
    string(14) "Master Plvmber"
    ["user_email"]=>
    string(24) "info@gatewayplumbing.com"
    ["user_url"]=>
    string(30) "http://www.GatewayPlumbing.com"
    ["user_registered"]=>
    string(19) "2007-08-10 20:40:53"
    ["user_activation_key"]=>
    string(0) ""
    ["user_status"]=>
    string(1) "0"
    ["display_name"]=>
    string(14) "Master Plvmber"
    ["spam"]=>
    string(1) "0"
    ["deleted"]=>
    string(1) "0"
  }
  ["ID"]=>
  int(1447)
  ["caps"]=>
  array(2) {
    ["subscriber"]=>
    bool(true)
    ["bbp_participant"]=>
    bool(true)
  }
  ["cap_key"]=>
  string(15) "wp_capabilities"
  ["roles"]=>
  array(2) {
    [0]=>
    string(10) "subscriber"
    [1]=>
    string(15) "bbp_participant"
  }
  ["allcaps"]=>
  array(4) {
    ["read"]=>
    bool(true)
    ["level_0"]=>
    bool(true)
    ["subscriber"]=>
    bool(true)
    ["bbp_participant"]=>
    bool(true)
  }
  ["filter"]=>
  NULL
  ["site_id":"WP_User":private]=>
  int(1)
}

1\. If the circulated water comes from the building, then as long as your units’ zone valves are open, the coils will get warm/hot. 2\. Zone valves are there to prevent the coils from getting hot in the absence of a call for heat. 3\. You’re forcing water up through your return for some reason. It happens. It has to do with the way the valves are arranged. Shut your return valve, open the supply and bleed. You may get different results that way.