Zone that doesn't heat properly

Gordy

I think you should try one thing at a time here to see if improvements are made with each change. Doing a bunch of stuff at once, and you won’t know what actually was the fix.

ntonkin

Now I see it in my manual too. Interesting with all the guys that I've paid to come here and fix this, none of them picked up on this error.

Gordy

Maybe when we are done you can teach them

ntonkin

Gordy said:

ntonkin said:

Do you think it would help to put the boiler pump on "low" speed?

Is the boiler circ a 26-99 which I believe comes with it? Is it 3 speed, and what speed is it currently on?

Yes it is a 3 speed 26-99 and I had it on medium but recently changed it to low. Just wanted to know if you think that was a bad idea.

Gordy

Well like I said I would make changes one at a time to see what works. You were getting a 20 delta on the primary side(boiler) at the separator.

You could drop the pump speed down to 1 first it would be easiest to try first. What you should see is a larger boiler delta which should not be more than 35, but with that pump on speed 1 may only be 25.

If it’s to slow the boiler may start to short cycle.

I have a feeling the system sensor is seeing a mixed temp instead of the actual system temp. Just going by the readings you provided.

However the boiler in, and out is seeing about 180 out with 160 return region so it could be the boiler flow. Slowing could allow a higher mix temp out to the system.

SuperJ

You want to minimize the boiler flow within its constraints. But right now your system sensor isn’t placed optimally so I would boost the primary flow until you properly locate the sensor. Boosting the flow will ensure the secondary supply flow consists mostly of boiler supply instead of being diluted with some in heated return. Once the sensor is propely locates the boiler can compensate for the mixed water temperature. A potential future upgrade would be to install a variable speed primary pump. Lochinvar is one of the few manufacturers that supports this. It modulates the pump based on firing rate to try and keep the return water temperature low and efficient.

If your delta is creeping over 35 or if the boiler is throttling on high boiler outlet temps then increasing the flow is necessary.

BTW, it still seems like there is something obstructing the flow in your hydro separator, since both the primary and secondary seem to short cycling back on themselves (boiler supply warming up the return, and building return cooling down the building supply).

ntonkin

SuperJ said:

Once you move your sensor you may notice the boiler supply is above setpoint, but the system/secondary supply should stay pretty close to setpoint. Make sure you get as good of connection as possible to the pipe and that you wrap it with some insulation. A bit of thermal paste can help with conductivity between the copper pipe and temp sensor.

I'm going to buy another sensor rather than take that one out as I would have to shut down the boiler - - right?

Gordy

Not a bad idea. I wouldn’t rule out the existing sensor is bad either.

ntonkin

SuperJ said:

Somethings not right with either the numbers or the separator.
If the boiler entering temp is greater than the return temp then the boiler flow is greater the secondary flow. If the boiler/primary flow is greater, then, the secondary supply temp will equal the boiler supply temp.

In this case boiler rwt is > than system return (implying higher primary flow). But secondary supply is < boiler supply implying great secondary flow.

I wonder if the mesh inside the separator is clogged with something which is allowing both the primary and secondary to recirc up/down their respective sides instead of flowing across horizontally like they should.

Here are the three options (what appears to be happening should not be possible which is a mix of 2 and 3 below):

So... to check this out, I'll have to take the separator out of the system. Right?

SuperJ

You might be able to remove one of the connections and peek inside with a flashlight. This will probably have to wait until you don't need you heat so bad since you'll be down for a bit.

I would get the new system sensor installed, and your pump speeds optimized after that, and then if you are still having unexplainable temp readings maybe look inside the separator.

Did you use teflon tape on some connections? if some tape travelled thru the system it could get stuck on the the microbubble coalescing media inside the middle of the separator, this would from a bit of a barrier between the boiler and system side.

Do you have a ball valve on the bottom? you could do a blow down into a pail and see what comes out.

ntonkin said:

SuperJ said:

Somethings not right with either the numbers or the separator.
If the boiler entering temp is greater than the return temp then the boiler flow is greater the secondary flow. If the boiler/primary flow is greater, then, the secondary supply temp will equal the boiler supply temp.

In this case boiler rwt is > than system return (implying higher primary flow). But secondary supply is < boiler supply implying great secondary flow.

I wonder if the mesh inside the separator is clogged with something which is allowing both the primary and secondary to recirc up/down their respective sides instead of flowing across horizontally like they should.

Here are the three options (what appears to be happening should not be possible which is a mix of 2 and 3 below):

So... to check this out, I'll have to take the separator out of the system. Right?

Gordy

I don’t think I’ve ever seen a separator screen clogged. Not saying it couldn’t happen, but I would try simple things first.

A separator is designed to trap dirt, and be removed through the bottom port.
It’s not out of the question the sensor in the hydro sep is giving a false reading they do go bad. The sensor should be moved to the correct location though.

SuperJ

One other thing. I don't want to be insulting but are you sure the hot boiler supply is piped to the top left side of the separator and the building return (bottom right) and boiler return (bottom left) to the bottom?

Both the boiler and building hot pipes should be on the top side of the separator, and the cold pipes on the bottom.

The boiler screen shows the boiler supply and system temp, do they ever match? Turn the boiler pump on high temporarily and see if they match when the pump is on high?

The sensor might be in a brass well. If it is you can just pull it out and fasten it to the pipe just to the right of the separator.

Gordy

I checked from the pics it appears to be plumbed correct. Also by the temp readings, and locations.

icy78

I would say ,do what @Gordy said. Then if all the other zones are valved off and you still get a poor delta-t with 170 degree average water temperature then you simply have lowflow through that loop. Pull the IFC.
But really three things have changed. A new boiler with different set points, possibly the hydraulic separator? Two more added zones, so at least three changes.

icy78

icy78 said:

I would say ,do what @Gordy said. Then if all the other zones are valved off and you still get a poor delta-t with 170 degree average water temperature then you simply have lowflow through that loop. Pull the IFC.
But really three things have changed. A new boiler with different set points, possibly the hydraulic separator? Two more added zones, so at least three changes.

well I was doing this on my phone and I missed a whole page of posts so I would say disregard this! LOL

hot_rod

Gordy said:

I don’t think I’ve ever seen a separator screen clogged. Not saying it couldn’t happen, but I would try simple things first.

A separator is designed to trap dirt, and be removed through the bottom port.
It’s not out of the question the sensor in the hydro sep is giving a false reading they do go bad. The sensor should be moved to the correct location though.

We had a large one returned that had a brown cotton glove stuck to the screen. That will reduce flow and is not factory installed

SuperJ

@hot rod_7 what's your thoughts on using the temp well for a boiler system sensor in the hydroseparator? Is it biased towards the secondary supply? My, concern is that it may not be in a position to accurately pick up the possibly blended secondary supply temp.

ntonkin

SuperJ said:

Once you move your sensor you may notice the boiler supply is above setpoint, but the system/secondary supply should stay pretty close to setpoint. Make sure you get as good of connection as possible to the pipe and that you wrap it with some insulation. A bit of thermal paste can help with conductivity between the copper pipe and temp sensor.

Don't have any thermal paste so sanded the copper and clamped the sensor to it covered with thick cardboard. I'll put a tee in with a proper sensor well next summer.

hot_rod

The well in the sep was intended to be used to operate the boiler, instead of just the sensor in the low water volume type mod consIt adds a small amount of capacity to a low water content type boiler, it was a request from one of the boiler manufacturers.

A sensor a foot or so downstream would be more accurate for supplying and adjusting actual SWT to the system.

Still with certain A to B side flow conditions and blending, it may send a higher operating temperature that you would like, both SWT and return to boiler. If it is a rare below design condition and 80% of the season you are returning low, condensing temperature I would not worry too much.

That being said, any zones system and systems with variable speed distribution and now boiler pumps will deliver constantly changing flow blending.

A buffer running a set differential, set boiler flow rate and loads pulled from and ODR control off the buffer might be a better option.

In a perfect system 120F would be max design temperature, so the condensing issue gets solved.

A generously sized indirect coil or reverse indirect could supply DHW and still leverage condensing mode operation.

ntonkin

Gordy said:

ntonkin said:

Do you think it would help to put the boiler pump on "low" speed?

Is the boiler circ a 26-99 which I believe comes with it? Is it 3 speed, and what speed is it currently on?

It is a 3 speed 26-99 and I changed the speed from medium to low yesterday. Was that a good idea or not?

SuperJ

ntonkin said:

Gordy said:

ntonkin said:

Do you think it would help to put the boiler pump on "low" speed?

Is the boiler circ a 26-99 which I believe comes with it? Is it 3 speed, and what speed is it currently on?

It is a 3 speed 26-99 and I changed the speed from medium to low yesterday. Was that a good idea or not?

Well since you moved the sensor, leave it on low for now and watch the boiler delta. If you can let the house cool off and then simultaneously call all zones and raise the boiler setpoint, you will get a worst case scenario for boiler. See if you can get it to run at 100% fire and compare the boiler in and out sensors, make sure they don't go more than about 35degF apart. If they do raise the speed a notch.

Let us know how the system runs with the sensor in the new position. I'm curious to see what all your temperatures read (boiler in/out and system supply/return).

@hot rod_7 that makes sense, thanks for the explanation. And validates the idea to move it downstream a bit on the secondary side.

ntonkin

after moving the sensor, system supply out of the separator went up to 160 and the return is 140 - - - that is a very significant difference!

SuperJ

Awesome, the boiler will run as hard as it has too, to keep that sensor at setpoint, it wasn't reading the actual supply temp before so it backed off before the system came up to temp. Now it knows exactly what the temp is and should be much more consistent.

What are your boiler temps in and out?

How's zone 3?

Gordy

ntonkin said:

Gordy said:

ntonkin said:

Do you think it would help to put the boiler pump on "low" speed?

Is the boiler circ a 26-99 which I believe comes with it? Is it 3 speed, and what speed is it currently on?

It is a 3 speed 26-99 and I changed the speed from medium to low yesterday. Was that a good idea or not?

Yes, but I would have did one, or the other first, and noted changes if any. Now that you moved the sensor, and there is marked improvement for the system supply. You could change back to original speed, and see if there is any difference. At least that would tell you if it was the sensor, or the pump speed.

Did you buy a new sensor, or move the old one?

Gordy

ntonkin said:

after moving the sensor, system supply out of the separator went up to 160 and the return is 140 - - - that is a very significant difference!

Now your AWT is 150. See if the zone in questions temps at the baseboard are reflected by this change.

Gordy

hot rod_7 said:

Gordy said:

I don’t think I’ve ever seen a separator screen clogged. Not saying it couldn’t happen, but I would try simple things first.

A separator is designed to trap dirt, and be removed through the bottom port.
It’s not out of the question the sensor in the hydro sep is giving a false reading they do go bad. The sensor should be moved to the correct location though.

We had a large one returned that had a brown cotton glove stuck to the screen. That will reduce flow and is not factory installed

Still a guy looking for that glove he lost

You would think someone would of had a look inside before sending it back..........

Gordy

What I’m finding interesting is the system temp read by the sensor in the hydro sep before it was moved read 165.

The boiler out was reading 170.

The sensor does not know it’s location in the system, only the temperature. So in my mind just moving the sensor to the supply pipe on the system side didn’t magically raise the system side supply temp. It’s only reading 5 degrees cooler than it was in the original location.

If no readings were taken after pump speed change it’s not diffinitive the sensor location was getting bad readings to where it affected the supply temp..

Gordy

This is why I like to make trouble shooting changes one at a time so you know what worked, and what doesn’t.

Another aspect is if outdoor conditions have changed. Warmer, or colder than when the issue was happening.

ntonkin

Gordy said:

This is why I like to make trouble shooting changes one at a time so you know what worked, and what doesn’t.

Another aspect is if outdoor conditions have changed. Warmer, or colder than when the issue was happening.

The outside temp is up to 13 degrees this afternoon.

Gordy

Been thinking. How often do all zones call for heat?

Apparently the problem zone has never stopped?

ntonkin

Gordy said:

ntonkin said:

Gordy said:

ntonkin said:

Do you think it would help to put the boiler pump on "low" speed?

Is the boiler circ a 26-99 which I believe comes with it? Is it 3 speed, and what speed is it currently on?

It is a 3 speed 26-99 and I changed the speed from medium to low yesterday. Was that a good idea or not?

Yes, but I would have did one, or the other first, and noted changes if any. Now that you moved the sensor, and there is marked improvement for the system supply. You could change back to original speed, and see if there is any difference. At least that would tell you if it was the sensor, or the pump speed.

OK with boiler pump on medium, the output was 150 and return was 132. When I changed it to low, the output started to rise and got up to 153 and then the boiler throttled down to 43% and it never went any higher. The return didn't go up any.

Did you buy a new sensor, or move the old one?

I have the two small zones set on low and the rest on medium. It's hard to tell if changes like this make a difference because it's like shooting at a moving target. The boiler seems to constantly change it's firing percentage.

I found that the system sensor would just slide out of the well in the separator. So I just took it out and clamped it to the supply coming out of the separator to the secondary (see picture).

Gordy

Yes I know about the moving target.

So basically you are back to where you just moved the sensor?

Monitor, and see if things improve. If not I'd drop the pump speed to one. Then monitor it.

When changes are made give the system time to reach equilibrium.

Intplm.

Seems theres some more talk about A obstruction. Possibly in the hydraulic separator?
How well does it blow down? Might be able to stick something up threw the blow down valve to clear it?
The comment of doing one thing at a time is good advice.

hot_rod

zone 3 running by itself should only require about .85 gpm based on the amount of radiation you indicated. I highly doubt the sep could be plugged to the point on not allowing 1 gpm thru it. I don't know where something large enough could get into it to block it 90%?
If so the boiler would probably be starved for flow also.

If the only change was the ZV to pump I still think you have a pump, or multiple without the checks inside. Just because they have a sticker doesn't mean they have a working check inside.

Here is an example of what can happen without adequate check protection on multiple pumped zones.

ntonkin

hot rod_7,
Looking at your screen shot brought to mind another issue I had about 3 weeks ago where zone 6 (the largest zone and last in line in the manifold) started heating without calling for heat. Pump wasn't running either. I cycled the thermostat back and forth a few times and it stopped. Sure looks like the check in zone 6's pump is either missing or not functioning.
Then a few days later the condensate trap in the boiler plugged up. I thought I had a serious problem as I had the boiler's annual service done 3 months previous and I know the guy cleaned the trap. Called Lochinvar Tech and he said the only way that could happen is if you had really dirty gas or were sucking debris in the intake. I watched the guy take the gas line apart during the annual.
Still don't know why the condensate trap filled up in three months. Any suggestions?

Gordy

Okay, I’ll buy into that. I thought you said that zone three worked fine. Until the new boiler was installed, and in doing that you added two more zones.

hot_rod

ntonkin said:

hot rod_7,
Looking at your screen shot brought to mind another issue I had about 3 weeks ago where zone 6 (the largest zone and last in line in the manifold) started heating without calling for heat. Pump wasn't running either. I cycled the thermostat back and forth a few times and it stopped. Sure looks like the check in zone 6's pump is either missing or not functioning.
Then a few days later the condensate trap in the boiler plugged up. I thought I had a serious problem as I had the boiler's annual service done 3 months previous and I know the guy cleaned the trap. Called Lochinvar Tech and he said the only way that could happen is if you had really dirty gas or were sucking debris in the intake. I watched the guy take the gas line apart during the annual.
Still don't know why the condensate trap filled up in three months. Any suggestions?

Ghost flow happens when pumps have inadequate check valve protection, the zone valve prevented that.
I'd take all the pumps out and check to see if they have valves and that they are clean.
Even shards of teflon tape will hold a check open enough to allow ghost flow and over-heat a zone.


They are what they breathe.

Whatever is in the air that goes into the boiler can show up in the combustion chamber and condensate drain. Tree pollen, aggressive chemicals attacking the metal, bird or animal parts

ntonkin

OK, I got the Grundfos Alpha2 pumps and put one in the problem zone 3 and the other in the largest zone 6 that had the TACO pump with a temporary back flow problem.

After looking at that check valve, I decided not to put one in the zone 3 pump as I had already put a PFP (back flow preventer) in the zone a while back. It looks to me like those check valves must restrict flow by a whole lot, maybe 50%. The instructions with the alpha2 says to initially run them at level 3 for a while to get the air out of the zones. . . so I did and the zone 3 without a check valve flowed 7 gal/min where the large zone 6 with a check valve flowed 2-3 gal/min, so there must not be significant obstruction in zone 3 or at least not anymore.

Would it be a good idea to put BFP's in the return lines on all the other zones and take out those check valves? The BFP I put in the return on zone 3 didn't look like it restricted flow at all.

My problem zone 3 is doing much better now but it's warm out now (in the 20's) so that really doesn't mean the problem is fixed.

After a few hours I set both pumps to the "AutoAdapt" setting and now zone 3 (smallest zone) flows 5 gal/min pulling 24 watts when it's calling for heat and significantly more heat is rising from the radiators. Maybe that fixed the problem. The zone 6 (largest zone) now flows 2 gal/min at 16 watts. Is it the check valve causing this large difference? . . . must be..

ntonkin

Intplm. said:

Seems theres some more talk about A obstruction. Possibly in the hydraulic separator?
How well does it blow down? Might be able to stick something up threw the blow down valve to clear it?
The comment of doing one thing at a time is good advice.

I blew out the trap on the separator and there was a bit of sludge in there. It only let out a small stream at first and then blew out and flushed mightily. There really wasn't that much crud in it.

I placed the system sensor a little over a foot from the secondary supply outlet on the separator.

SuperJ

Are you getting consistent supply water temps to all your zones now with the new sensor location?

If the pump is serving a single zone with no downstream control valves, I think you should run your pump on one of the 3 fixed speeds or constant pressures. If you find one speed is too much, and another too little go with the higher and throttle a valve a bit.

The AutoAdapt mode is an learning adaptive pressure control mode. It's designed specifically for systems that have some sort multiple downstream control valves (specifically TRVs). Since your zone doesn't have changing characteristics besides the temperature AutoAdapt will just add some inconsistency.

I'm a big fan of AutoAdapt in the right circumstances, but I don't think it fits your system.