Buderus142/24 with S120 indirect DHW - Temp (Economy) Tank Relief Triggers

My propane tank was empty when I woke up this morning so the boiler wasnt heating the house. They refilled the tank, we reset the boiler, baseboard heat came back. However the hotwater tank relief triggered and flooded the basement.
Hot water is set to economy, per the manual that tells me the tank should stay at 140 and relief valve should trigger at 200 (per tag on valve).

I reset the DHW to economy to get the tank up to temp then turn it off. When I set to economy the temp continues past 140 and triggers the relief tank valve at 185.

Sounds like bolier is heating too much for DHW, doesnt matter what I set that dial to for the record. But why is relief valve triggering early too?

Anyone's help would be appreciated, technician support in my area (19403) is limited from what I've been able to come across so far.

 

It sounds as though you are talking about an INDIRECT water heater? and the relief valve on THAT, NOT the relief valve on the boiler... correct?

The water heater valve is temperature AND PRESSURE triggered.

We need to clarify something though... before we go off down the wrong track...

Tell us the make/model of your water heater...

 

I have a Buderus 142/24 that was convert in 2005 to propane. There is a stand-alone DHW (DIN 4753) and I believe it holds 31 Gallons. Model for DHW tank is s120.

 

OK, we know what equipment you have now...

As I said previously, the relief valve on the water heater is triggered by BOTH Temperature, AND/OR PRESSURE.

How do you know that the boiler is heating the temperature past 140 ?

How do you know that it is not the PRESSURE part of the relief valve that is opening?

You may require an EXPANSION TANK on the water heater cold domestic inlet line.

 

i believe i have an expansion tank, if it looks like a small propane take for gas grill, there is one in line.

the digital display and analag temperature are moving up in parallel when i move DHW dial to economy or higher, when the water hit the relief valve its at least 185 as it comes out steaming hot.

 

You will have an expansion tank on the HEATING BOILER, of course. But the question is, do you also have an expansion tank on the DOMESTIC COLD WATER feed to the S120?

There are relief valves on BOTH the heating boiler AND on the domestic heater. Which one is opening?

Which temperature displays are you looking at? Typically, there will not be a temperature gauge on the domestic water heater. You may be looking at the temperature on the HEATING BOILER.

If you haven't guessed, I am still unclear whether you have a problem with your HEATING BOILER relief valve, or your DOMESTIC WATER heater relief valve.

Can you take some pictures worth 1000 words?

FREE ACCOUNT at Image hosting, free photo sharing & video sharing at Photobucket ... upload your pics there, and come back here and place a link to your PUBLIC album. Please include CLEAR, IN FOCUS, WELL LIGHTED, and LARGE ENOUGH for old dudes to see... and take a few from a distance in addition to some closer ones...

 

ill get some pics, the relief valve that is opening in on the hot water tank, not comiong off the actual buderus bolier.

 

OK, will wait for pics...

In the meantime... when the relief valve opens, if you open a hot water tap, does the relief valve stop flowing?

 

Pictures by mcanavan05 - Photobucket

Relieve valve on blue water tank is what triggers. digital display is reading 185 when it starts to drain steaming hot water. Dial would be set to ECO. (Why doesnt that stop at 140 on ECO?)

 

The display is probably showing you the temperature of the water in the BOILER, and NOT the temperature of the DOMESTIC water in the tank.

 

The water out of the relief valve on the tank is steaming hot, bottom of plastic bucket is hot when i have to move it to empty it.

Not sure if there is a sensor in the tank thats bad or the relief valve is shot?

I assume thie boiler has to go up to whatever 185+ degrees to ensure the 32 gal tank is measuring 140 deg since ECO mode calls for 140?

One other note, I had a contractor add the outdoor sensor for temp. He said that is only for the baseboard loop and nothing to do with DHW tank.

 

That's correct. The boiler water that circulates through the coil in your water heater has GOT to be hotter than your target temp for the domestic water.

What happens if you switch out of the ECO mode and try a straight 140 setting? or even the AUTO setting? same problem?

Are you sure that the sensor did not get pulled out of the 'well' in the water heater when you were working around it? The wire from the sensor is dangling... maybe something got caught and pulled on it? That would cause a problem!

Also correct.

 

doubt the wire was tugged on as this seemed to coincide as to when the propane tank went empty, so I guess I'm down to senser in tank replacement and or relief valve. Guess relief valve is needing replacement if the steaming hot water is measured below the 200 deg temp noted on the ring/tag of the valve?

I appreciate your help, been more help than most that have come on site.

 

BUT... with the setting at 140, there is NO WAY that you should have 185 coming out!

You keep going back to that relief valve... and TEMPERATURE...

HOW DO YOU KNOW IT'S NOT OPENING ON PRESSURE?

That relief valve is a COMBINATION temperature AND PRESSURE part.

Please CHECK THAT THE SENSOR IS FULLY INSERTED INTO THE WATER HEATER... DO NOT ASSUME !!!!!

 

maybe it is pressure, when i toggle through the display it shows p16 to p19 from time to time. Could losing the boiler burning change the state of pressure in the system once the bolier had no propane to burn. This thing failed over the course of the night, no idea what time it happened as we were sleeping.


this so called german energy efficient box with outdoor temp sensor irritates me sometimes.

 

The pressure display on the boiler panel bears no relationship to the pressure in the domestic water system.

There are only two things that will open that relief valve: Temperature and pressure.

Both are easy enough to measure. You need to know which one is the cause before troubleshooting anything. Otherwise it's a guessing game, and that's not the way to troubleshoot anything.

You can pick up a pressure gauge for about $10 at HD or Lowes that screws onto a hose bib. Screw it on to the drain on the water heater and open the drain to read the pressure. It has a needle on it that records the highest pressure seen by the gauge. Leave it in place for like 24 hours and see what the max pressure reads. If it's at or above the relief valve setting, you have your answer... if it's NOT real high, then you need to measure the temperature of the water. Probably can do that first, as I'm betting that you have a meat thermometer in the house... don't just guess... take data and diagnose.

 

I measuerd the hot water from faucet 131F

Did a load of laundry and kept hot water on faucet going to try to reduce water in tank and therefore have ECO setting kick in...it did. It fired and displays (digital and analog) on bolier were reading 195, my theremometer was ready 189-190 on water coming out of relief valve. Believe the relief valve is rated for 200.

 

I need to look at your pics again...

How can the water from the tap be 131, and the water from the relief valve be 190 ? It should be the same temperature! I wonder if they installed the relief valve in the wrong pipe?

 

no idea

Pictures by mcanavan05 - Photobucket


the tap i used was the bathroom downstair less the 15feet away from boiler and tank.

how could that be possible problem now? was installed on 2005, never had isssue til now, ive been in this house since end of 2007.

 

After reviewing the installation manual, I can say without a doubt that the relief valve is installed in the totally WRONG PORT of the water heater.

Take a look...

http://www.buderus.us/files/20100120...AMI_072001.pdf

Refer to Figure 4 for port designations, and Section 4.2 ... the third step which says to install the relief in port AB ... your relief valve is installed in port VS, which is one of the pipes to the boiler.

How did it work all this time? I have no idea... but it is definitely opening on TEMPERATURE, as you suspected... but it's in the WRONG HOLE! Of course it will open on temperature! The boiler water IS that hot!

So, what can you do in the meantime? Turn down the temperature of the heating circuit. If you lower the boiler water temp below the opening point of the relief valve, it won't open and you can continue to use it until you have a chance to have it repaired properly.

Don't drag your heels though... it's somewhat DANGEROUS to run the water heater without a proper relief valve! You've been lucky so far.

 

wow..im beat, and i agree with you, it is in wrong port. So i bet when the contractor put the outdoor sensor in, he pushed up the water temp of the boiler a little. No with the weather it running hotter in general? I know that are suppose to be seperate but i didnt have this issue for 2 other winters.

 

Yeah... something changed to run the boiler a little hotter.

It was your measurement of the water temp that made me notice it! Good job!

I'm not highly familiar with your boiler control... I did read through it yesterday... but looking at it again, should the right hand knob maybe be on AUTO ?

 

ill set it to auto and call it a night for now. There another controller that was wired in and its behind the whole bolier cabinet that I have to take off. I think that is where the real setting needs to be adjust for the outdoor sensor. I think the contractor said the right hand knob was basically out of the picture now since the outdoor sensor has that internal setting to work with.

really appreciate the help. think a fix is around the corner, guess best way to do it make adjustment to either right hand dial and or get into internal controller and make setting change there..assume i just need to be 180 or less since 185 trips it.

luckily im moving the whole unit into my garage in the spring.

 

I don't know that it's SUPPOSED to be set to auto... I just read the book again and it's very cryptic! I think AUTO will allow 190F as a max... so you might just want to turn it back to 170 and go from there...

Have a goodun...

 

I set it to auto or 170, doesnt matter. I dont believe it is kicking on in ECO mode. Could the sensor be bad and therefore not know when to call ECO/140 from the boiler? If the sensor is bad would that reduce the high temp of water into tank?

For now, I'm tripping the tank to heat by switching to ECO and letting the relief valve fill the bucket. Then we shower, laundry, etc.

Regardless this valve is in wrong port, this issue never occurred in the 3+ yrs I've been here. Last winter was worse and it didnt happen...

 

The boiler water temp must have been turned up. Turn it down under 170. So it will quit tripping the temp relief. You dont want that hot water spraying into that bucket. Thats boiler water. Not the water you get out of your tap. You must be adding a lot of fresh cold water to your boiler. Thats not good ! It might damage the boiler.

 

The boiler has the AM10 outdoor sensor on it now. Does the boiler water temperature dial still have control, i.e - set to 170? or Does the AM10 really run the boiler water temp at this point?

 

Dont know the answer to your question, but how much fresh water is being added to your boiler every day ? How much water in the bucket ?

 

The relief valve will trigger til just over 2 gallon is generated. I know because I left in ECO mode and forgot only to come back and have bucket totally filled and some on the floor. Thats the best I could tell.

 

Its the boiler temp tripping the releif. Not the DHW tank setting.

ECO, what is this economy setting ?

You got to get that boiler temp down so it quit tripping the releif.

Or better yet you must move that presure relief valve (PRV) to the right spot like trooper said.

AND SOON, like tomarrow !

The way it is now there is no PRV on the hot water tank ! It could blow up if overheated or over pressured !

 

ECO should call for hot water to the tank and maintain at 140F, suppose to help save propane from always having it fire up.

Assume the water temp from boiler to DHW is too hot and that is causing relief valve to trip. pressure doesnt seem to be an issue.

 

Do you plan on replumbing that PRV ?

 

Yes, I do plan on replumbing the relief valve correctly.

 

There is probably a setting on the ODR unit that determines the BOIL MAX temperature. It may well be possible to access that setting and lower it. If as your installer said the front panel control is no longer in command... that would be what you need to do... let me see if I can find some specs on that ... maybe you can easily change that.

The ECO mode for the domestic heat maintains a wider differential... 18° versus 9° in the other modes. Should result in longer time between firings, and the firings may be a little longer... when they do occur, but overall may result in a net savings.

 

Ive read the AM10 outdoor sensor and even made adjustments there. My contractor is coming out Fri, I told him about 191 temp on relief valve water, he know's it not plumbed correctly. Hope this will solve it. Still wondering if AM10 impacted incorrectly plumb..sucks since i Have to pay to fix this, then pay to move it this spring.

 

From what I can see, the HIGH LIMIT setting on the boiler control panel should still be in command no matter what the AM10 is telling the boiler. If it's not, then someone goofed something up... from what I read at least.

Do you know how to access the settings on the AM10 module? If so, can you tell us what the settings currently are?

Here's a link to the PDF file I"m looking at:

http://www.buderus.us/files/20100122...UserManual.pdf

Note section 1.2 page 4 where it says:
I believe that a call for DHW will BYPASS the heating curve and the boiler will heat to it's high limit setting if needed.

 

Why? is this installer the one who made the error by installing the relief in the wrong port?

If so, he should not have you pay for his mistake.

 

No, this contractor did not perform the DHW tank install, he's helping me get moved next spring. I cant check the setting now since i'm not home. will check tomorrow and let you know. I appreciate the help.