Entire System backflowing ??

LearningFromTheBest1

Is the entire System is backflowing? All radiators get warm when any of the six zones call for heat. The system has operated properly for 20 years, What happened?

mattmia2

We need way more context, but a failed flow check?

LearningFromTheBest1

What info would be helpful, Details, Pictures? Thanks, Rick

mattmia2

Pictures of the boiler and its piping such that we can see how it is zoned and controlled. Maybe a picture of a radiator.

LearningFromTheBest1

Let me know if you need more pictures. Thanks for the help.

mattmia2

In you first picture there is a flow check on each zone, the brass things with the knurled knob on the top. Any chance they are in the manual open position, did someone work on the system and open them to purge the system or something?

pedmec

can you take a pic with the boiler and piping all in one pic?

LearningFromTheBest1

Two of the Flow Check valves were replaced in April, the others are original and all are
in the closed position. Can the entire system (all zones) back flow when only one or two check valves fail?

pedmec

Check to make sure that the ball valve on the system bypass is opened. It looks like they messed up the primary/secondary piping plan and its working more like a system bypass. Using the tekmar to modulate the temperatures to the zones. The ball valve needs to be fully open. if its closed the circulator on the right of boiler will force water thru the system. ITS PIPED WRONG

hot_rod

I don’t think it was intended to be primary secondary?  It’s just a parallel boiled zone pump system. The bypass is probably a low temperature protection method. Looks like a low temperature zone via a HW thermostatic mix valve?
The tekmar is a boiler control? What is the model number? It should have boiler protection.
Really shouldn’t need that pump on the boiler return? 

What size is that boiler? It could be micro zoned causing short cycles?

And yes every pump needs to have a check or working flow control valve

LearningFromTheBest1

I checked all the ball valves, they were OK.
Last month the the Tekmar 260 diagnostics were run. No issues.

Summary 10/22
When any zone calls for heat, one zone (circulator pump) operates properly, however all the radiators are warm. The entire house heats up.

Mechanical Info. New Installation in 2001
Boiler- 2001 Utica DV200B 200,000 btu
Boiler Controls – Replaced in 2009. Tekmar 260
Hot Water Maker – Replaced in 2017. Amtrol Boilermate CH-80Z
Primary Panel - 2001 6 Terminals, Erie Zone Track SR601
Secondary Panel – 2001 3 terminals, Erie Zone Track SR301
Note 4/22: Five Grundfos UP15-42F zone pumps and two of the watts ¾ 200s-M5 flow check Valves were replaced. My son did the work. 25yrs and very capable.

ZONES
#1 Hot Water Maker 80 gallon
#2 Master Bedroom – Cast Iron Baseboard
#3 Garage – 8ft Radiator
#4 Front corner Bedroom and Rear Corner Bedroom – Cast Iron Baseboard
#5 Radiant - Kitchen and adjoining Family Room
#6a Split Zone- Sunroom –Cast Iron Baseboard
#6b Split Zone - Available (not used)
#7 Available (no pump)
#8 Living room and Dining room - Cast Iron Baseboard

hot_rod

No piping changes since it was installed?
Something suspicious about that circulator on the boiler return, improperly mounted by the way🤓
when does that run? Is it wired to the tekmar boiler control?

It looks to be in series with all the zone pumps and could push open the pump checks when it runs? Maybe the relay that controls it is stuck on. With a volt meter see if that is running constantly. I think it is meant to be variable speed based on return temperature. If the speed control function is bad and it runs 100% that could be causing the unwanted flow
20 years on a control…?

If the garage 8’ zone or sunroom call, does the boiler short cycle?

hot_rod

Here is the piping from the manual. Usually a single pump system with zone valves. That crossover is a work around with zone pumps, I suspect

pedmec

@hot_rod 1 agree, mostly. If you were going for system boiler protection you really wouldn't need the boiler circulator on the return and not a full size system bypass. That's why i think they intended for p/s with the tekmar for reset.

hot_rod

It is piped per the installations, problem is the zone pumps instead of valves 

The 360 was probably intended to control the boiler SWT on outdoor reset function, not a a return protection 

Regardless, if it has worked for 20 years, look for something that has changed.

If the boiler pump is running 100% speed all the time, I think it will flow all zones.

Certainly a simple thing to try, unwire the boiler pump and send a single zone call for heat

mattmia2

Or that bypass valve I assuming is behind the vent is in a different position than it was for the past 20 years.

pedmec

@mattmia2 That has to be the issue. how else do you get heat all zones?

mattmia2

The boiler circulator being on a variable speed control that has failed at full speed as @hot_rod suggested or some debris that is holding the flow checks open is another possibility.

pedmec

That would be so wild to have 6 flochecks hung up with debris all at the same time, lol. But i guess anything is possible. But the circulator running 100%. I wonder now if maybe the ball valve has been closed all this time and its a three speed circulator and someone changed the speed to high like bob said. it think that's an easier scenario to happen than closing that ball valve. either way that boiler circulator is causing the flow.

LearningFromTheBest1

Thanks for all the input. The piping may not be perfect, but the system has performed very well for 20+ years with no problems. Something has changed. I'll check the boiler pump (same Grundfos pump as the zones) and see if it runs all of the time. The change has to be something that causes all zones to make heat when only one zone pump is running.

P.S. The DHW maker ran properly all Summer without any any sign of any overheating, but if any zone calls for heat the entire house heats. Is that relevant?

LearningFromTheBest1

Additional info-No piping changes, The circulator on the boiler return is wired to the Tekmar boiler control.

neilc

that boiler circ should be mounted with the motor horizontal, like all the zone circs,
not vertical like it is

mattmia2

like others said, try disconnecting power to the boiler circulator and see if it goes away.

LearningFromTheBest1

Bingo!! Disconnected the pump and the System works as it should. My son had mentioned that there might be a a short in the panel a few days ago. My Bad. We will trouble shoot the panel and repair/replace. Thanks for all the help. You input was very much appreciated!

Question: The Boiler controls are from 2009, no wi-fi. Considering upgrading the boiler controls. Any suggestions for replacement controls (Brand/Model) ?

pedmec

I don't think a short in the control would be your answer as a short on the board would most likely cause a complete failure of the tekmar control. The internal relay is obviously functioning as the circulator is turning on with a demand for heat or hot water. The question is why is the circulator coming on every time on demand? I believe that the outdoor temperature sensor has most likely failed. Every time there is a heating demand the boiler circulator is on. When the outdoor sensor is functioning the boiler and circulator will only come on to maintain the loop temperature based on the heating curve. The screen should say open. If the sensor fails the default value it uses is 32 degrees.

mattmia2

Disconnecting the circulator was diagnostic. Now you need to answer why this didn't happen before.

The 3 possibilities are:
1. The bypass valve is more closed than it was before the work was done on the system.
2. There is a variable speed control on the boiler cirulator and the semiconductors have shorted so it is full speed all the time.
3. The circulator is a multi speed and is set to a higher speed.
4. (I guess there is a 4, the circualtor was never working).

LearningFromTheBest1

The buy pass valve handle was removed when the system was installed. I believe the boiler circulator, a Grundfos, UP15-42F, is single speed. I don't think there a variable speed control on the boiler circulator, but I am not sure. Something is causing the boiler circulator to run. Perhaps the circulator on the boiler is running due to a faulty sensor or some other electrical malfunction, as suggested by pedmec

mattmia2

Try opening the bypass with the boiler circulator running then closing it back to where it was, maybe some debris got stuck in it.

hot_rod

I suspect the system would run fine without that boiler pump working, try it!

You don't have primary secondary piping, so its not a primary pump.
It is not in a position to be a boiler bypass pump.
You have a piped boiler bypass, for some reason?? It could offer some protection by just adjusting the valve and allowing some bypass, without that pump.
It is in series with any/ all the zone pumps, so it adds unnecessary head.

The tekmar control is just acting as an outdoor reset control for boiler temperature.
It only controls that boiler pump pump because it is intended to be a control for a single pump system with zone valves.

With your zone pumps, any one would supply enough flow for that cast boiler.

With a cast boiler and high temperature emitters how much are you curving the boiler temperature? I doubt you would go much below 150 SWT, up to 180 on design day?

Usually when you program a control like that you write down the parameters you entered in the manual to know how it was set or to make minor tweaks.

pedmec

My theory is that if the OA sensor has failed it is no longer changing the temperature based on accurate outdoor temperature. it will default to 32 degrees according to tekmar. So every time there is a demand from the zone controls the tekmar is turning the boiler and circulator on, or the circulator is coming on from the internal boiler relay. So whatever temperature 32 relates to on the curve the boiler is going to run until it hits that target temperature.

Or somebody has changed the curve. either way.

i would open the tekmar and see if the boiler is fed from 7 and 8 on the tekmar terminal control. this way you will see if the tekmar is controlling the boiler circulator.

Its in position for a system bypass, not boiler bypass

hot_rod

He mentioned that the boiler pump is wired to the tekmar. I think it has a 2 minute post purge also, which may push some addition flow past the "off" circs.

I still see no need for the boiler pump. If you replace the control get a model with return protection if that is even needed?

What type of radiators? You could disconnect that pump, close the bypass, turn all zones on from a cold start.

If the boiler return temperature reaches 130F within about 10 minutes, really no need for the bypass or that pump. You could still use a ODR control, but when it is in mild weather, supplying only 150 or so, the return temperature may not get warm enough, or quick enough.

It really depends on the type of radiation, low mass or high mass, and radiation amount compared to boiler output.

The radiators control the boiler operating condition.

LearningFromTheBest1

The System (Boiler Controls) behaves like it is being given erroneous information. Maybe it is the Outside Air Sensor? How to test it?