The water coming out of my Burnham Revolution boiler seems too cold . It is at most 130F. Yet the internal temperature indicator shows 170F. This is even with only the water heater running (even the hot water was hotter than that) .
I suspect the internal variable speed pump, yet wonder how I can troubleshoot that as there is also a mixing sensor and a control board. How are these pumps driven (wiring??).
I noticed that these pumps get 3 wires. Would there be a way I can connect these and circumvent the control board. That way I could at least validate that this pump still works.

Any suggestions are appreciated,
Thanks, Oskar

 

Oskar, first let me ask the obvious... is the home heating properly ? In other words, was there a reason you began looking around ?

What is the aquastat set on your boiler ? The Revolution series requires that it be set to something like 200° if memory serves...

We've got at least one Revolution owner on board who will surely be by soon to offer advice. There are others here who know those systems very well...

I wouldn't suggest trying to jimmy up any kind of bypass for the controller...

 

Hrmmm... You might want to check the sensor first with an ohmmeter.

rbeck should know.

 

First thing to check is the aquastat setting. For the Revolution, it should be 210F. Any lower and it could result in the symptoms you describe. This is because the aquastat has a 30F differential off the high limit (IIRC) and setting to the 180F of a standard boiler means that you will never see the internal circ come up to speed, and the boiler temp will be low as well.

First, here's how the Rev works.

When T-T is energized it starts the circulator wired to the vs3000, which is energized by C1 off the aquastat. The fan comes on and has to prove before the gas valve is energized.

The vs3000 control will turn on the internal circulator and begin to pull some of the return water in the bypass down through the boiler and back out to the bypass. The outlet temperature of the water leaving the boiler and back into the bypass is monitored with a thermistor which tells the control what that temperature is. The control evaluates the temperature at the boiler outlet pipe and modulates the pulse and width frequency of the AC current being sent to the internal circulator to make it run either faster or slower. When the temperature of the water in the boiler is below 165F the pump can be slowed down to as much as 13% of its normal speed to slow the internal flow down to allow more exchange of heat from the boiler. As the temperature rises up through 170F the pump will begin to ramp up in speed until the full speed is eventually reached. If another zone with cool water turns on and the internal temperature of the boiler again drops, the pump will slow down a bit to allow more heat exchange. The visual indication of the approximate internal pump speed is the bottom LED of the vs3000 board. If it is blinking slowly the pump is running slowly and you will see it start to blink faster as the temperature rises through 170F until it remains solid on, at which point it's at full speed.


Warning: the following is armchair advice from someone who's never messed with the vs3000 wiring on one of these boilers, and is electrically challenged to start with. Here's how you can bypass the variable speed, and have constant full-speed, as I understand it. This could be completely wrong!

Turn off the power. Remove the wire from terminal 3 of the vs3000 and put it into the same terminal as the wire going into terminal 1 and then turn the power back on. Be careful not to bridge terminals 1 and 2. By moving the wire from terminal 3 to 1 you are sending the full frequency of current to the pump all of the time. i.e., constant high speed.

By doing this, you are defeating the variable-speed injection scheme that protects the boiler. This should be for testing purposes only. Leaving it like that could lead to bad things happening in the boiler.

 

Xiphias, thanks for the detailed explanation.
NJTrooper: no, the home is not heating properly anymore. The kickspace heaters did not kick on anymore and the warm water heat exchanger kept asking for heat as the incoming water temperature from the boiler was below the setpoint (hence I lowered its setpoint...).
I did not check the sensor with an ohm meter yet. Did check the reported voltage on the vs3000 controller. That was reading 3V.
The lower control LED on that same controller was blinking about once every 3 seconds. Not sure if that is a normal rate.
I turned up the aquastat to 210F. Noticed that the internal thermometer indicated that the water there is reaching 220F. I guess I have to be careful with overshooting.
Yet the outgoing temperature (for like the waterheater) is still much lower than 2 days ago (like Thursday). It is now reading about 150F, still not the 180F I saw before....
Did notice though that now the kickspace heaters kick on. So at least now I might be able to get my house to the desired temp.
Xiphias: regarding the variable pump speed. Even though the internal thermometer is showing over 220F and the aquastat is set for about 210F, I do not see the led continuously on. It keeps blinking in 3 sec intervals. Would that mean the the control circuitry is not setting this pump to full speed when it should?

All, I really appreciate the feedback as I have already twice (March 2006 and March 2007, I moved into this house in Oct 2005) had a plumber come over. Before he would come I had switched off the system. The plumber would come, switch it all on and seemed happy with its performance. He would then leave leaving me a bill of about $200... Yet nothing repaired... . So I would like to try and avoid this experience by trying to figure out what is really happening here.
Does anyone know a good plumber who is up to speed with Burnham boilers in the Northern Boston area?

Again, thanks for the quick replies,
Oskar

 

Oskar, you don't need a plumber... you need a technician who is trained properly on this equipment ! A tech who has been to Burnham training courses would be preferable.

You might get a recommendation here, as a few members are in your vicinity...

 

NJ trooper: you are probably right.
Xiphias: I checked the resistance of the thermistor: 2.2K Ohm. Is that what it (about) should be? The temps were about: 190F internal, output water was reading about 170F (to 180F, slow thermometer there...).

I did the following test: Disconnect the thermistor from the control unit. This causes the control unit to:
1/ blink the top LED (I guess indicating failure)
2/ Set the pump to full speed (exactly what I wanted).
When doing this, the output water temperature seems to much better follow the temperature read from the internal thermometer!!!
This seems to indicate that either there is something wrong with this thermistor, or there is something wrong with the controller. Does not seem to be an issue with the pump.....

As soon as I reconnect the thermistor to the controller, the top light (power) goes solid again, and the bottom light (control?) starts to blink at 3 secs intervals again. Almost indicating not sufficient power to the pump.

Is there an issue if I, for a few days, just disconnect the pump? Would I then risk condensation issues?

Oskar

 

Disconnecting the internal pump will probably have the exact opposite effect of what you are trying to achieve.

The internal pump circulates the hot water out of the heat exchanger, and blends it with the system water. Take a look at that 'manifold' on the boiler. See where the "Y" shape is ? The hot water coming out of the boiler blends in the area between the Y intersection and the Tee to the left of it.

Do you have the manual ? I think there is a chart in there that will tell you what the various LED are communicating. There is also a chart in there that will tell you what the resistance of the thermistor should be at various temperatures.

Have you cycled power to the unit since re-adjusting the a'stat to 210° ? That might clear any 'fault codes' that were stored.

 

Burnham Revolution Installation and Operation Manual

Table 13, bottom of page 79 is the chart for the thermistor.

2.2K is probably around 145°

If this is what the thermistor is reading with 190° water, then there is definitely a problem with that... the internal pump will run at low speed, thinking the water in the heat exchanger isn't getting hot enough, yet by all indications, it is...

From what you've shown so far, it looks as though the thermistor could be the culprit.

 

NJ trooper, thanks for that info. Stupid enough I had already downloaded the manual long time ago , forgot it contained this kind of info. Thanks for finding that. I'll definitly check that thermistor again.

Regarding the pump. I did not disconnect it. By disconnecting the thermistor (not the pump) the control unit switches to run the pump at full speed.

I must say that so far (last couple of hours) the system has been working great with this hack.

Now where can I find a new thermistor. I guess a phone call Monday to Burnham is in place.

When looking at the diagram on page 74, it seems the water temperature sensor for this control unit is not in this section. So does it measure the water temperature inside the boiler (in the heat-exchanger)? If so, it will be hard to verify that with another measurement. Although, if the outside measurements are already over 170F, then indeed this thermistor should have a lower resistance....

Again, thanks NJ trooper for this info.
Oskar

 

First, a caveat. Again. I'm a homeowner 'hydronic hobbyist.' I don't troubleshoot this or any other boiler. I don't mess with the fire side of things. This is water side, so I'm more comfortable, but given how this boiler is designed to work with the internal circulator, messing around with these controls could lead to bad things happening. I fully agree with Trooper's suggestion to find a knowledgeable tech. Plenty of Burnham guys in the greater Boston area.

My first guess is a bad thermistor. I assume you were using a good-quality ohm-meter (~50k capability), and measuring the thermistor per p. 79 in the manual (i.e., thermistor disconnected from control). If you were getting 2.2k ohms and seeing 190F on the manifold temp/pressure gauge, that doesn't seem right. Table 13 in the manual says it ought to be ~977 ohms at 190F.

If the thermistor is telling the vs3000 that it's seeing 2.2k ohms, that's equivalent to ~145F, which is well below the temp at which the pump starts ramping its speed up (see above operation description in earlier post). Flashing lower LED every 3 sec would be a pretty slow speed. So the vs3000 never sees ohm values that tell it to speed up. Sounds like a bad thermistor.

I would not disconnect the internal circulator. If you do, then lower the aquastat to 180F. Maybe 190F. You probably don't want this boiler core getting 210F hot and just sitting. Your zone/DHW circs will not be able to draw out heat fast enough. If you're getting hot enough water (~140F) to run the toekicks, then I'd live with it like it is until you can get a new thermistor. Flow through the boiler is a good thing!

Earlier you said you adjusted the aquastat to 210F. That suggests that someone messed with it in the past. If the manifold temp gauge is going to 220F, then there is probably a little error in either or both the aquastat and that gauge. Might back off the aquastat a tad just to be safe. An IR thermometer is a good thing for checking this.

 

Ok, I misunderstood what you said about the pump. You were wondering about disconnecting the thermistor ... that's different!

I guess it would depend on your system whether or not you might expose your boiler to condensation issues. If your return water comes up to temperature quickly, I doubt you will have a problem with it, at least not for short term. I also doubt it will hurt the controller. It can't hurt the pump.

That thermistor is sensing the water temp in the heat exchanger, not out in the system. The thermometer on the Y branch inside the boiler should agree with the thermistor reading. If the VS3000 'thinks' that you have 145° water based on that 2.2K reading, then it will always be running on it's lowest speed. It only starts ramping up the speed after it sees 160° temps.

Can you see the sensing end of the thermistor ? It hasn't simply come loose from the pipe for some reason, has it ? Might wanna take a look, could be a simple fix. Just took a look at the manual again, it appears that the thermistor may be mounted in a well pictured on page 92, item 6F on the drawing. There's another well pictured on page 82, item 1E. I don't see anything in the repair parts that calls out the thermistor though!

 

Trooper -- a quick study you are, young man!

Oskar -- Running the circ at full speed all the time may leave you in the condensing range long enough to cause condensation in the heat exchanger. I would live with it as is until you can get a new thermistor.

I agree with Trooper that it might just be a seating problem in the well.

 

Thanks! but don't forget that I studied that manual a while back when we were talking about YOUR VS 3000 !

Whippersnapper callin' _ME_ young !

 

Sorry was out of town a few days and missed this post. You guys have pretty much nailed it. If sensor was mounted on the pipe it could have come loose. The nylon ties were brittle after awhile and breaking. The sensor was later moved to the casting for accuracy and more stable mounting. The newer VS3000 will get to full speed about 160f and reduce flow to 7% at minimum. The older boards the lights were flush and the newer ones the lights protrude from the board.
You have verified you circulator is running but for future reference I check circulator by verifying 120v to board. Let boiler get cool. Disconnect the circulator wire 3 on the VS3000. Let boiler get to limit and shut down on high temp. Turn boiler off, connect wire which was removed from terminal three to terminal 1. This will supply 120v to the board and circulator. Turn switch back on and carefully check temperature at the supply side of the boiler. If it gets hot instantly the circulator is working. If it does not the circulator is not working.
This goes along with all the previous posts

 

Very helpful all this feedback!!! Thanks to you all.
I thought I send some pics so you can see the setup. Biggest issue is that the side I have to work on is very close to a wall. So will be hard to get to.
See this link:
http://www.boschjes.com/boiler

Any thoughts on that water temperature sensor? How easy that will be to replace? Does it look loose???

Again, really appreciated all the answers and feedback.
Oskar

ps: how to put a picture inside a post???

 

Well, your pressure gauge says 0 psi. That's not good, for starters. Add water until you get to 12-15 psi. See if that improves things. You may be close to dry-firing this boiler. Not good. Potentially dangerous.

 

Oskar, that device you believe to be the water temperature sensor is what I believe to be the 'Differential Pressure Switch' that is intended to prove the blower is running before the boiler will fire.

The thermistor probe will look 'something' like this, but it may be inserted into a 'well'.


photo courtesy
thermistor.com

Yes, you've got more than one problem ... and it may be related to the low pressure. It is very possible that the sensor is reading wrong because it is not in water ...

Fix that FIRST!

You must have 12-15 PSI on the boiler pressure gauge, see where that red 'telltale' needle is pointing ?

While the pressure is at zero, and before you put pressure back in, it is a very good time to check the status of the air charge in the expansion tank. Using a good quality tire pressure gauge, measure the pressure on the tire valve on the bottom of the expansion tank. It should be 12-15 PSI. If it is not, add air to that valve with a small air compressor or a bicycle pump until it is.

Then find the reason for the low system pressure.

 

I consider that almost criminal to install that boiler without any access to those components! How would one ever even _think_ about replacing the internal circ ... it IS one of the things down there, isn't it ? Yes, I believe it is ... someone should be SHOT ...

Another thing that is VERY disturbing to me is:

In the picture "Overview of the plumbing" , it appears to me that the valve with with red handle, coming off the pipe at the center of the boiler is in line with the SAFETY RELIEF VALVE ! So, could someone un-knowingly close that valve, and prevent the relief valve from operating in the event of a high pressure condition ? That would be such bad practice as to shoot someone TWICE! Am I seeing what I think I'm seeing ? or is that yellow tag obscuring my view ?

Back to the pressure problem... behind that red handle valve, there is a beige colored thingy, with a handle on top of it. That is your "pressure reducing valve", and it feeds the water into your boiler, while reducing it's pressure from the city pressure to 12-15 PSI for your boiler. Following that 1/2" pipe back to it's source, at some point there should be a manual valve ... is that valve OPEN ?

 

Pressure gauge reading zero: this gauge is not working. I had to mount another gauge (see overview picture, middle left) to actually get the real pressure of the system. That gauge is reading between 15 - 20 psi. So the pressure of the system should be fine (note that the gauge I mounted has a range up to 160psi, so it is not that accurate in this lower range. This was the only gauge they had at the store...).

Regarding this shutoff valve right before the pressure relief valve. That is my doing. Thought it would be easy that way in case I had the replace the pressure relief valve in the future. Guess that makes it not up to code....

Locating the temperature sensor. I look at the boiler some more to try and find it. Makes sense that I only photographed this pressure differential sensor.... hhmmm.
Just found the temperature sensor. It was just hanging loose right next to the outlet from the heat exchanger. Does anyone have any hints on how this sensor should be mounted?
See this link with some more pics inside:
http://www.boschjes.com/boiler/tempsensor
(what a pain to get in there......)
I guess though that this loose temperature sensor explains it all. But now, how or where do I mount this.... It does not look like any from the picture from NJ Trooper...

 

Which location is your sensor located? I am not blowing off the importance of the pressure as it is a problem. It also may be your only problem. Bring the pressure and and problem may go away. If not where is the sensor located?
http://s246.photobucket.com/albums/g...ngManifold.jpg

 

rbeck: thanks for reminding me about the picture. I guess I have to open up the system somehow.

 

Ooops! Sorry Oskar, I won't pull the trigger !

But, do this at least: Remove the handle, hang it on a nail somewhere. Tag the valve with a note in big letters "DO NOT CLOSE WHILE BOILER IS IN OPERATION!" That oughta take care of that...

 

You don't have to open the system up to get water into it. There is a feeder there somewhere. A quick scan I did not see it where it belonged which is feeding between the bladder tank and the system.

 

How about this one ?




photos courtesy
thermistor.com

 

rbeck, I think Oskar is talking about opening up the system to re-mount the thermistor ?

He mentioned that the gauge inside isn't working and that he has one mounted externally, and that the pressure is OK ...

Rather than mounting that thermistor on the nipple between the flange that bolts to the boiler block, and the flange for the manifold, do you think it would be acceptable to mount the thermistor right in front of that flange with a couple ty-raps ? And then a piece of pipe insulation over top of it ?

Sure would be easier, and I bet _almost_ as accurate ?

 

If the sensor is on the pipe it must be on top and touch the casting for proper operation. Another reason it was moved, to sense water temp better. Not a big improvement but picked up a few degrees.

 

Oskar, I bet that little 'yellow' sliver that can be seen in one of the photos, behind the attaching flange is what's left of the ty-rap that used to secure that sensor to the pipe.

Is there enough room around that sheet metal, and are you a good enough contortionist to bend around and re-mount that sensor in the original location ?

I am quite sure that even if you do temporarily mount that sensor on the pipe in front of the flange that it will work 'reasonably' well, until you can get in there and do a proper fix.

rbeck, do the older boilers have the tapping drilled and plugged ? or is it absent on them ? If it is present, would it be possible and/or worthwhile for Oskar to do a retro-fit ?

 

Rather than using a ty-wrap I would suggest using a worm-gear type hose clamp. Put some heat conductive paste between the pipe and the thermistor and don't tighten the clamp more than just enough to hold the thermistor against the pipe. Wrap the installation with fiberglass.

 

It was not drilled and tapped in earlier versions. That is the sensor hanging there. This is a waste of fuel. The boiler gets hot (limit) but circulator does not get to max speed. It is not that hard to get to. I have fixed a few. I have used screw clams with a thumb screw. Put clamp on and tightened so the sensor is snug to push under. Then worked sensor under and one small twist. It will not come loose again.
Furd's idea may work. Never tried it. Even if it would be off a few degrees it would be OK with the newer VS3000

 

It's so close to that wall, I'm surprised he could even get the camera in there to take the picture ! I just hope nobody has to ever change that boiler circ ! I didn't look at the minimum clearances in the manual, but I'll bet some tech only used it to keep the knees on his knickers clean.

I just looked at the manual again ... Burnham says minimum clearance to that side is 4" ... that's just plain sadistic !

 

4"? Ha. I'd be amazed if there's 1" there. Definitely not a setup that's designed for maintenance. Bummer. At least the problem appears to be the thermistor. Whew.

Is the water feed allow to be piped into the pressure relief?

 

Let's not confuse clearances to combustibles as service clearances. Most manufacturers refer to combustibles but not service clearances. That is a non-combustible wall so there is no minimal clearence for combustibles. That does not mean it can be serviced. It is normally up to the tech to determine how much room he needs for servicing. Some jobs look like the tech has tools and may know how to use them but no common sense when it comes to the installation.

 

Hose clamp seems indeed the best as plastic does not go well with the heat.
Regarding remounting the temperature sensor. As the unit is used a lot right now (low temps outside, in lower 20's) I'm going to wait until I can easily shutoff the system for a couple of hours. Spring sometime I guess. It is too hot in there to do anything. Especially with the limited access I have (already burnt my hands a bit, both of them!!! ).

Regarding the controller (VS3000). How do I know which version I have?

Oskar

ps: thanks to all your feedback I'm actually starting to understand how this thing works and have great working heat at this time. Many many thanks for that (got a family of 5 here, with kids from 3 yrs - 5 yrs).

 

If you can somehow wedge the thermistor between the pipe and one of the flange nuts and then apply some fiberglass insulation, even just shoving a wad against the thermistor, it will likely work as it should.

 

Oskar, all you have to do is take a cable-tie and strap the thermistor to the top of the supply outlet pipe where it is hanging. Just don't crush it. If you have a piece of Armaflex (the gray/black foam pipe insulation), put that over the thermistor to protect it from being crushed. That should give you a close-enough reading for the pump to get up to the proper speed.

Shouldn't take more than 2 minutes.

 

Xiphias, you are totally right. In a normal setup would not take more than 2 minutes. With my setup though, the wall blocking almost all access, I have to sneak around a lot of hot pipes. Hence the wait till the weather gets warmer.

 

It's gonna cost ya in increased fuel Oskar !

Even if you just went in there with some duct tape, it would be better than leaving it hanging ! (duct tape might fall off though, from the heat)

Even a plastic zip-ty will last the rest of the season... c'mon, at least get it in contact with the pipe a little bit !

 

I have a Revolution. I did a test run going in from the front panel. If you turn off the boiler for 30 minutes the exhaust pipe will cool off and you can get your fingers in there without burning your wrists on the exhaust pipe and put a tie-wrap with armaflex over the sensor.

Just scootch the sensor up to the top of the pipe and cinch it down. Gently use a pair of needlenose pliers, a hemostat, a pair of chopsticks, or a coat hanger bent into the shape of a long forceps will work, to move the sensor into position and you can largely avoid touching the supply pipe (which after 30 minutes is still pretty warm).

Not as easy as going in from the side, but it worked.