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Zone that doesn't heat properly

123457

Comments

  • ntonkin
    ntonkin Member Posts: 135
    edited February 2019
    SuperJ said:

    It would be helpful to note the set point (or is it always 165f). What zones have the highest flows and temp deltas? I wonder where all your heat is going with the boiler at 100% with only 3 zones calling.



    Make sure readings are taken once things have reached equilibrium.

    SH1 is set to 165, SH2 & SH3 are set to 125 - this is what the tech put in at the initial setup.

    The only zones I can get a flow reading are 3 and 6 - the ones with the Alpha2 pumps. I just got four more strap-on thermostats so I will get them on and get some delta's.

    What exactly do you mean by "equilibrium" ? Is it when all the zones stop calling for heat? Then I get a "set point met" message or a "standby".

    When I got home this evening, the boiler message was "set point met" and no zones were calling and the boiler output temp was the same as the system temp.
  • ntonkin
    ntonkin Member Posts: 135
    firing% 100
    boiler in 148
    boiler out170
    system 158
    delta T 21
    flue temp 839
    Secondary out 146
    Secondary return 132
    zones calling 5 (garage)
    Outside temp +20
  • ntonkin
    ntonkin Member Posts: 135
    Gordy: I had to back the "throttling" off a little as I was getting a "blocked" error on the screen and the boiler had shut down.
  • Gordy
    Gordy Member Posts: 9,546
    equilibrium is the point where the emitters are heating well, and it's close to the end of when the room set point is reached.

    If you take the measurements when the heat call first starts everything is a bit skewed as boiler, piping, and emitters are trying to reach that equilibrium.

    Stand by is basically set point was met, and boiler is idle. You don't want to do any readings during that point.
  • Gordy
    Gordy Member Posts: 9,546
    edited February 2019
    As far as your strap on locations at the emitters. Just give the temps going in, and coming out. That's relevant to me. The delta is not.
  • Gordy
    Gordy Member Posts: 9,546
    ntonkin said:

    Gordy: I had to back the "throttling" off a little as I was getting a "blocked" error on the screen and the boiler had shut down.

    That's fine. I was expecting as much. Is it a ball valve? If so how much is it closed?

    Also you only have one radiant zone?
  • ntonkin
    ntonkin Member Posts: 135
    Gordy said:

    ntonkin said:

    Gordy: I had to back the "throttling" off a little as I was getting a "blocked" error on the screen and the boiler had shut down.

    That's fine. I was expecting as much. Is it a ball valve? If so how much is it closed?

    Also you only have one radiant zone?
    Yes, it is a ball valve and I now have it a little less than a quarter closed.

    One of my zones is pex in the concrete garage floor (zone 5) and zone 1 has 3/4" copper pipe under the concrete floor (not in contact with the concrete) the pipes are in little trenches setting on a 4" wide by x 1" thick strips of foam with tinfoil over the top of the foam. all covered by soil with lines 18" apart AND then the pipe goes into two 8' baseboard radiators. I can isolate the floor and run only the radiators but it seems to heat quite nicely with them both running together.
  • Gordy
    Gordy Member Posts: 9,546
    On that zone 5, if you run the supply to the baseboard first then to the floor you would get some better output from the baseboard, and then the cooler water to the floor. But if it works nicely so be it.

    One more reading, and then see what we get. Is the boiler cycling at all during these readings?
  • ntonkin
    ntonkin Member Posts: 135
    Gordy said:

    On that zone 5, if you run the supply to the baseboard first then to the floor you would get some better output from the baseboard, and then the cooler water to the floor. But if it works nicely so be it.

    One more reading, and then see what we get. Is the boiler cycling at all during these readings?

    firing% 100
    boiler in 123
    boiler out147
    system 141
    delta T 19
    flue temp 170
    Secondary out 140
    Secondary return 122
    zones calling 3 & 6
    Outside temp +25

    The boiler has been on "standby" quite a bit this morning as it has been warm.
  • SuperJ
    SuperJ Member Posts: 609
    Those numbers make more sense then the ones I've seen before. Looks like the system flow is slightly exceeding the primary flow.
    ntonkin said:

    Gordy said:

    On that zone 5, if you run the supply to the baseboard first then to the floor you would get some better output from the baseboard, and then the cooler water to the floor. But if it works nicely so be it.

    One more reading, and then see what we get. Is the boiler cycling at all during these readings?

    firing% 100
    boiler in 123
    boiler out147
    system 141
    delta T 19
    flue temp 170
    Secondary out 140
    Secondary return 122
    zones calling 3 & 6
    Outside temp +25

    The boiler has been on "standby" quite a bit this morning as it has been warm.
  • Gordy
    Gordy Member Posts: 9,546
    Yes they do except it appears to be the start of the heat call as boiler out is only 147. Let's take a couple more when you get a chance to see if there is some consistency.

    This run is zones 3 and 6 noted.
  • Gordy
    Gordy Member Posts: 9,546
    edited February 2019
    As to those 4 strap on thermometers. Calibrate them on a same section of pipe to see if they all read the same. Preferably by the well thermometer on the system supply. The strap ons might read a bit lower.

    Also what is the location of the system sensor in reference to the ball valve on the system supply? Before the valve, or after?
  • ntonkin
    ntonkin Member Posts: 135
    edited February 2019
    Gordy said:

    As to those 4 strap on thermometers. Calibrate them on a same section of pipe to see if they all read the same. Preferably by the well thermometer on the system supply. The strap ons might read a bit lower.

    Also what is the location of the system sensor in reference to the ball valve on the system supply? Before the valve, or after?

    The system sensor is clamped on right after the valve and a strap-on thermometer is right before the valve. I got some thermal paste and will do a better job of clamping the sensor to the pipe later this afternoon.

    firing% 100
    boiler in 154
    boiler out176
    system 154
    delta T 21
    flue temp 198
    Secondary out 151
    Secondary return 150
    zones calling 1, 2. 3, 4 & 5
    Outside temp +26
  • ntonkin
    ntonkin Member Posts: 135
    Gordy said:

    Yes they do except it appears to be the start of the heat call as boiler out is only 147. Let's take a couple more when you get a chance to see if there is some consistency.

    This run is zones 3 and 6 noted.

    The boiler has been on "stand-by" a lot this morning - it's in the mid twenties outside and also the living room floor radiates heat.
  • ntonkin
    ntonkin Member Posts: 135
    firing% 98
    boiler in 164
    boiler out186
    system 169
    delta T 22
    flue temp 191
    Secondary out 160
    Secondary return 149
    zones calling 6
    Outside temp +25

    I've started trying to calibrate the strap-on thermometers and here again, it's somewhat of a moving target with the system sensor as a reference; the thermometers respond so much more slowly as compared with the sensor.

    Also, I got the new thermostat installed in zone 3 and the sensor redone with the thermal paste.
    Still haven't got the thermometers calibrated.... it's looking like within 5 degrees may be the best I can do.
  • SuperJ
    SuperJ Member Posts: 609
    Once you've got your thermometers calibrated make a note of the offsets. You want to see how the compare to each other and the system sensor. This is important if you are going to try and use them to set about zones to based on temp deltas.

    Leave the primary flow alone, I think we need to dial back the secondary flow, but it will be an iterative process.

    First can you get a supply (system sensor) and return temperature reading from each zone at steady state and report back (the return from the mixing valve might be extremely low). That will help identify which zones might have excessive flow. They will tend to have low temp deltas.

    On your garage zone, you want to set the manual mixing valve just barely warm enough to keep it at setpoint on a cold day. This will take some trial and error. It's better to trickle a continuous stream of warm water, than it is to blast hot water in occasionally.
  • Tom_133
    Tom_133 Member Posts: 883
    Side note, I noticed you ran your exhaust vent in PVC and you are getting really close to 200 degrees on your flue temp. Just be cautious of that. I’m not saying you can or cant just be mindful of the ratings.
    Tom
    Montpelier Vt
    SuperJ
  • Gordy
    Gordy Member Posts: 9,546
    edited February 2019
    Let’s dial down the secondary a bit with that ball valve after the separator on the supply I mentioned earlier. About 1/4 to start with.

    This will slow the flow to any zone/s that are calling. I believe all zones are over pumped, and the separator is rated for 11 gpm. So when you get more than one depending on which ones the sep isn’t mixing properly.

    As you can see when all zones but 6 were calling your secondary supply temp went down.

    When only zone 6 is calling in the last one the system went up.


  • ntonkin
    ntonkin Member Posts: 135
    edited February 2019
    Gordy;
    I "throttled" the secondary supply 1/4 while the boiler was on "standby". Next time it fired up the readings were:
    firing% 100
    boiler in 147
    boiler out 170
    system 159
    delta T 23
    flue temp 185
    Secondary out 156
    Secondary return 151
    zones calling 3 & 6
    Outside temp +15

    Right after the firing started dropping back, the boiler in got up to 184 and boiler out to 185
    Remember, you had me put all zone pumps on their highest speed.
  • Gordy
    Gordy Member Posts: 9,546
    What was the system out?
  • Gordy
    Gordy Member Posts: 9,546
    Yes I remember.
  • ntonkin
    ntonkin Member Posts: 135
    Gordy said:

    What was the system out?

    return from system was 151 degrees
  • Gordy
    Gordy Member Posts: 9,546
    System sensor out.
  • ntonkin
    ntonkin Member Posts: 135
    156
  • ntonkin
    ntonkin Member Posts: 135
    Do you want me to take all readings just after the firing rate starts to drop from 100% ??
  • Gordy
    Gordy Member Posts: 9,546
    I think we need to go a different route.

    I'm trying to save you 700 dollars in flow setters.
    I thought maybe we could throttle the main secondary to all pumps. That’s not going to work. So open it back up.
    It's hard not being able to do a realistic head loss calculation on each zone to see where you fall on it's pumps curve.

    Right now you are over pumping the hydro sep in my opinion, and the mixing isn't going well. The sep is good for 11 gpm.
    On speed three each pump if there were 8' of head is pumping about 10 Gpm. Even on speed one each pump with 5' of head is about 5g. So if more than two zones are calling it’s going to put you over.

    So let’s get drastic. Drop all circs to speed one in the morning, and take some readings. We might have to throttle zones from there as I think even speed one is to much with multiple zones calling.
  • ntonkin
    ntonkin Member Posts: 135
    edited February 2019
    firing% 100
    boiler in 145
    boiler out 169
    system 154
    delta T 24
    flue temp 188
    Secondary out 154
    Secondary return 148
    zones calling 3, 5 & 6
    Outside temp +18

    This was before making the above changes.
  • Gordy
    Gordy Member Posts: 9,546
    edited February 2019
    Okay let’s give it a try. Drop to speed one on all the secondary circs, and take some readings for the next go around.
  • ntonkin
    ntonkin Member Posts: 135
    firing% 100
    boiler in 136
    boiler out 159
    system 151
    delta T 21
    flue temp 185
    Secondary out 154
    Secondary return 150
    zones calling 3, 4 & 5
    Outside temp +20
  • Gordy
    Gordy Member Posts: 9,546
    Is this another reading as it was, or after pump speed changes?
  • ntonkin
    ntonkin Member Posts: 135
    firing% 100
    boiler in 167
    boiler out 189
    system 168
    delta T 20
    flue temp 198
    Secondary out 162
    Secondary return 120
    zones calling 5
    Outside temp +21

    The last two readings are with the pumps at speed 1 and no "throttle" on the secondary and only a little "throttle on the primary.
  • Gordy
    Gordy Member Posts: 9,546
    Okay.
  • ntonkin
    ntonkin Member Posts: 135
    firing% 100
    boiler in 158
    boiler out 178
    system 168
    delta T 20
    flue temp 197
    Secondary out 163
    Secondary return 158
    zones calling 3 & 5
    Outside temp +23
  • ntonkin
    ntonkin Member Posts: 135
    firing% 100
    boiler in 166
    boiler out 187
    system 169
    delta T 20
    flue temp 195
    Secondary out 161
    Secondary return 120
    zones calling 5
    Outside temp +23
  • SuperJ
    SuperJ Member Posts: 609
    Looks like zone five is linked to the wrong demand signal on the boiler. Should be linked to one of the low temp sh2 or sh3.
    160f is probably not required for indoor PEX.


    Zone 3 is moving too much water. I'd close the ball valve half way on 3 if the pump is already at min speed.
  • ntonkin
    ntonkin Member Posts: 135
    SuperJ said:

    Looks like zone five is linked to the wrong demand signal on the boiler. Should be linked to one of the low temp sh2 or sh3.
    160f is probably not required for indoor PEX.
    Could you give a reference on how to switch this over to SH2?

    Zone 3 is moving too much water. I'd close the ball valve half way on 3 if the pump is already at min speed.

    At fixed speed | zone3 is flowing 3 gal/min according to the pump display. What should I reduce it to?
  • Gordy
    Gordy Member Posts: 9,546
    The trick from here is to throttle all the zones so they heat effectively yet not over power the hydro sep when all are calling.

    Any zone with baseboard should only need between 2-4 gpm. Favor 2 to keep air entrained.

    The radiant zone 5 has flow meters. I don't know what flow they are set at, but the loops should be running between .5, and .75 gpm. So you could throttle that pump to where the flow meters are still showing the indicated flow you are set at.

    The zone with the copper pipe in floor, and baseboard may take a little experimenting. Maybe 2-4 gpm.

    Now is a good time to use those strap ons to check supply in and out on loops to see where you are at.
  • Gordy
    Gordy Member Posts: 9,546
    does the boiler ever modulate down? Seems odd it's always 100-high 90's percent.........
  • ntonkin
    ntonkin Member Posts: 135
    Gordy said:

    does the boiler ever modulate down? Seems odd it's always 100-high 90's percent.........

    Yes it does sometimes; but mostly it goes from "standby" to 100% and then backs off to 20% or so and then back up - sometimes not all the way to 100% - - it depends on what zones are calling. I have been recording when it goes up to 100%, not when it's lower. Do I need to follow another strategy?
  • Gordy
    Gordy Member Posts: 9,546
    Okay. I was just wondering since your data always showed 100%.