Zone that doesn't heat properly

ntonkin

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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.

Gordy

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

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

What was the system out?

Gordy

Yes I remember.

ntonkin

Gordy said:

What was the system out?

return from system was 151 degrees

Gordy

System sensor out.

ntonkin

156

ntonkin

Do you want me to take all readings just after the firing rate starts to drop from 100% ??

Gordy

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

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

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

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

Is this another reading as it was, or after pump speed changes?

ntonkin

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

Okay.

ntonkin

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

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

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

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

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

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

ntonkin

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

Okay. I was just wondering since your data always showed 100%.