Injection problem

Tim Doran

Was the balancing valve on the injection return line full open? If it was it may be the problem. The sensor is seeing a large slug of hot water and it reacts by turning the injection pump off. It will short cycle the pump to the point that the loop will not heat even though the injection supply is hot.

Tim D

Terry

Injection Probs

Getting calls on a few systems that appear to be piped properly, yet the secondary loop would not heatup until a valve was cutin between the injection tees to force injected water into loop. (otherwise the injection line was HOT, yet the secondary loop would not heat up)

Has anyone else seen this type of reoccuring prob? and what is the reason/solution?

all apllicable rules to injection piping have been applied. all pipe diameter distances match criteria... has me stumped..

pls help if you can..

Terry T

Dann Crist

I would like to see

a diagram, somethings not right-- I use injection quite frequently, pumps must be located properly--also check to
see if the injection pump is wired correctly ( you'd be surprised!!!) It may not be running at all. What injection control are you using???

John Jr

Picture

Can you provide a picture of the piping? The only thing that should create what you are saying is the balance valve being closed.

John Jr

Bill Wright_2

or ...

the "system sensor" is not located so that it is seeing a "mixed" temperature.

Terry

Terry

diagram

this drawing shows piping config & also wiring for the tekmar controls. Used 356 vari-speed daisy chained to 255 Boiler Control.

COnfirmed that balancing valve was open & pump was running. Injection line HOT, yet secondary loop wouldn't heat up. (has now, but only with another vlv cut in between tees on secondary)

a huge thank you in advance to all you helpful wallies !

Terry T

Bill Wright_2

Diagram hard to read, but ...

I would approach it in the following manner:

Potential culprits:

1.) Control is bad: push the test button & verify that the control goes through the correct sequence per the manual.

2.) Radiant side sensor is not reading correctly: measure the resistance across the sensor (or across 17 & 18), compare reading to desired water setpoint (100 F = 5,828 ohm, 120 = 3,760 ohm). To make this easier, you should set the left dip switch to "setpoint" (up) and then set Max/Setpoint dial to the desired water temp. It could be either a bad sensor (which has been known to happen) or the sensor is too close to the Tee's & therefore is not truely reading "mixed" temperature.

3.) Reset curve is not properly setup: turn reset off & see what the control does (does the radiant supply start to warm-up?)

4.) Cold Slab Start-up: inital slab start-up (should only last between 4 to 40 hours depending on conditions). Probably not a factor in this case -- but check to see if the Min Return light is lit (after checking the position of the Minimum Boiler Return dial).

Just some thoughts -- I hope they help,

Bill Wright

Terry

i will check

Thank you for the input. at least now I have a starting point. I will advise what I find.

Thanks again.

Tim Doran

The other thing

To think about is sensor location and velosity. I would suggest that the radiant supply sensor be placed after the pump to ensure that proper mixing has occured. If the velosity is fairly low at the injection tee the flow may be "laminer" which means that it may not blend well and it can cause inaccurate readings, hot spots and cold spots, etc.

Tim D

hr

You can actually hear

the pump change RPMs. I use a screwdriver against the pump and the handle end against my ear. Push the test button and you will hear the motor run through the rpm range.

You could have a stuck pump.

hot rod

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eleft(retired)

stuck pump

> the pump change RPMs. I use a screwdriver

> against the pump and the handle end against my

> ear. Push the test button and you will hear the

> motor run through the rpm range.

>

> You could

> have a stuck pump.

>

> hot rod

>

> _A

> HREF="http://www.heatinghelp.com/getListed.cfm?id=

> 144&Step=30"_To Learn More About This Contractor,

> Click Here to Visit Their Ad in "Find A

> Contractor"_/A_

eleft(retired)

That's my experience.

Stuck pump!

al

Dann Crist

I vote on the side of a stuck pump, but original post states that this problem was called in on a few systems. If true, then a stuck pump is not likely the problem for all these systems, Perhaps sensors are wired to the wrong places
one guy told me he wired the "system" thermistor to the outlet of the boiler and the "boiler" thermistor to the inlet of the boiler??????????? Oh well, we all gotta learn and I've made enough errors to know I don't know it all!!!!!!!

Dann Crist

if thermistors in right place

then I vote w/ Tim Doran

marc

air bound system

you probably have air in injection lines or system pump.