accurate reading of supply sencor

Robert_15

Hello, i ended up putting a Honeywell Immersion Well utilizing an 1-1/4" x 1/2" x 1-1/4" c-fip-c tee in the supply, it works very well the next thing i did was off the supply after the circulator i ran a 1" pipe to the return with a ball valve. the return temp is keeping the temp much more accurate then when i used the boiler bypass, so i shut it down for now and will see if i need to use it. My settings on the odr is set to 135 low 170 high outside temp to 10 i was wondering the best set temp. on the high end? or if i adjust the outside temp to a lower degree would i be able to lower the supply temp that way?
Thanks

Robert_15

The supply sencor seems to be not accurate at the two locations i have placed them. the first time was about a foot from the circulator at the tee, two zones about 15 f difference. then at the supply about 2 feet after the first elbow below the ball valve seems closer in temp but still off. the instructions say in the shell of the boiler but where do you put it. any suggestions to where i should place the supply sencer
thanks

Mike T., Swampeast MO

No boiler tapping to insert the sensor?

Brad White_9

When you say

'not accurate', do you mean it drifts or hunts in temperature? Or that it reads differently than another means you are using?

It is common for one means to vary from another. I use a Pete's Plug and digital probe thermometer within six inches of a control sensor. That seems to align best in my experience. But if surface mounted or in a well can make a huge difference, several degrees at least.

If in a tee (especially in an immersion well with the bulb pointing into the flow) the circulator location should be fine IF it is at least seven diameters if not more, downstream from the mixing point. It is the proximity to any mixing point that is most critical. Are you reading after a T-Mix?

(I take it you are reading the supply to the radiation loop not the boiler here.)

I assume the sensors are installed in a well. Have you used heat conductive paste? Insulation? All good practices? Curious.

Brad

Robert_15

It is a burnham hot water boiler. i do not think so, that would be the best. what i have been doing is setting the boiler aqaustat to 180 and let the O.D.R control work from there but the sencor does not shut off the odr for a few min. later
thanks

Robert_15

Hi brad this sencer is on the black pipe. I am taking the measurment with a thermonenter on the supply as well by circulator. i do relize that the sencer would work best in the shell but ther is no ports that i see. i was thinking about putting it in where the relief valve comes out of the top of the boiler though the hole resting on top of the heat plate but i do not think that would work

Brad White_9

Scott,

I would not place the sensor in or near the relief valve tapping just in principle. If it is boiler temperature you are reading, you want an area of constant circulation so the supply riser off the top ("the black pipe" I believe you are referring to) should be ideal. Not too close to the jacket though.

I have similar sensors on my old boiler, used with a Honeywell Centra system installed in 1986. This is what I did for that and recommend for you:

Draw-file the pipe to bright metal. Then dip the sensor in conductive paste (Honeywell Tradeline or other), strap it to the pipe with an SS hose clamp and insulate over it with Armaflex for the first layer and finish with an over-layer of whatever insulation you are using. Fiberglass in my case. Or a second layer of Armaflex with offset joints.

When you say you measured with a thermometer, the kind with the spring strap- those only say that you have some temperature (LOL). Infra-red types? They are not accurate unless the pipe is painted. The will read near room temperature on bare metal that is 300 degrees. (The metal reflects infra-red, not emits it apparently. Contradictory? Sure. But I have seen this.) Either of those devices may have led you to seek advice.

If all of this is for OA reset, your boiler value will be read as well as could be and you can also adjust the curve for any perceived skewing in accuracy. But this should not be more than five degrees I would say.

Robert_15

Thanks Brad so after the second elbow above the adjusted ball valve but before the bypass piping would be good. i tried to find the conductive paste in H.D. but they did not have it i will look at Blackmann's for it. right now i have the supply senser just below the ball valve not enough flow because of the troddle back of the ball valve it is wraped with foam tape and strapped. but i think when i had it at the elbow just after the cerculator the temp was off more because of the bypass with cooler water flowing to that point. i have a multi tool with a wire to the outside of the pipe it seems accurate with the readings. with the adjust of the temp i did lower the odr to 170 and the boiler temp going to 180 i think maybe i should adjust the odr to 168 may work better,

Brad White_9

I think you are on to it now, Scott

Firstly, it will not take too much flow to get a reading from a sensor on a pipe that is insulated. The throttling effect of the ball valve on temperature reading is miniscule.

Secondly, you are correct that to measure the boiler as a true value you do not want any bypass.
(I have to ask though, how are you maintaining minimum flow through the boiler? I do not know what kind you have but am just checking. It may or may not be an issue.)

Thirdly, you are reading by comparable means, surface to surface using thermistors. All things being equal, you are doing the best anyone could without insertion wells and all we have discussed.

Fourthly, you are prepared to skew the curve as you need to.

Good going!

Brad

Robert_15

brad

HI Brad this is a c.i. boiler with the boiler bypass having the supply ball valve adjusted to keep the return around 130 sometimes it goes down below 90 but it goes back up and stay's above 130. it is a little frustrating to get that ball valve just right. on the bypass ball valve i leave the valve open very cool water coming through it. so do you think leaving the supply senser right before the ball valve or should i move it above it?I guess there is no way of putting the supply senser into a burnham without a tapping?

Unknown

Scott

Depending on the brand of the control, I like to see the supply sensor immersed in the flow of water on the supply main. Unless this an MPO boiler, there really is no accurate place to put it on the other boilers. When it is in an immersion well in the flow of supply water, it gives you a very accurate reading. Mine is on the supply pipe in a Honeywell Immersion Well utilizing an 1-1/4" x 1/2" x 1-1/4" c-fip-c tee. It is held into the well with the clip that is provided with the immersion well. Never had much luck strapping sensors to the mains as the reading is never that accurate. Hope this helps.



Glenn Stanton

Manager of Training

Burnham Hydronics

U.S. Boiler Co., Inc.

Robert_15

Hi Glenn The boiler is the p205 I was going to lower the boiler control from 190 to 180 i think 180 is hot enough right?it is a shame the boiler could not have that fuction for the supply senser

Brad White_16

Glenn-

Does Burnham offer in the residential line the return water protection package (valve and pump) as you do on the commercial V-11 series among others? I am thinking from Scott's posting that he is adjusting the bypass manually when a 3-way valve (with packaged harness) might be more responsive to the real variable -temperature.

Unknown

Sensor Location

Scott, If you have a bypass then you wouldn't want the supply sensor in the boiler. It is what it's name inplies....a "supply sensor" and it should be sensing just that. Even though I don't need to use it, I have a "boiler bypass" on my MPO boiler. The supply sensor is in the supply flow just after the bypass connection.

Glenn Stanton

Manager of Training

Burnham Hydronics

U.S. Boiler Co., Inc.

Unknown

Sensor Location

Scott, If you have a bypass then you wouldn't want the supply sensor in the boiler. It is what it's name inplies....a "supply sensor" and it should be sensing just that. Even though I don't need to use it, I have a "boiler bypass" on my MPO boiler. The supply sensor is in the supply flow just after the bypass connection. It is there to sense the temperature that will be needed to satisfy the reset control when either a call for heat or DHW is active independant of any bypasses.

Glenn Stanton

Manager of Training

Burnham Hydronics

U.S. Boiler Co., Inc.

ChasMan

If you have not found the conductive paste yet, Radio hack has it. As do many Computer parts places. Nice install BTW, If I could find someone who does that stuff around here Id have a lot more spare time on my hands. Is that Baro mounted on a T or did you make a collar yourself?

Unknown

RTC Control

We have adapted the RTC control to a few of the larger residential boilers on special applications but in reality it is a bit overkill. There are too many simpler methods of protecting the boiler such as boiler loops, primary-secondary, variable speed injection, etc.. The residential boilers don't encounter the aggressiveness that the larger pressure fire boilers endure.

There is a lot of temperature in the firebox and flue passageways of pressure fire boilers in relation to the size or mass of the boiler and water content. That is why it is of utmost importance to maintain the proper flow through the boiler in an effort to maintain a proper Delta T. The RTC monitors return water temperature that the boiler sees coming back from the system and the control will due whatever is necessary to guarantee that the return water never drops below 135F by means of a properly sized pump, properly sized piping and a motorized diverter valve. The RTC requires the boiler be piped in primary-secondary to the system. In essance, it is a fully modulating "system bypass" with return water sensing right at the boiler. It is way overkill for a P205 boiler and besides, Tekmar makes controls and valves that do the same thing on a smaller scale. Here is a photo of a V9A setup with the TRC control. Hope this helps.

Glenn Stanton

Manager of Training

Burnham Hydronics

U.S. Boiler Co., Inc.

Unknown

ChasMan

The barometric is mounted on a tee. I think that the paste you are referring to that Radio Shack carries is Heat Sink Compound. It is a white consistancy and is used to help a heat sink dissipate it's heat. I used to pick up a tube every once in a while to use on my Triumph Bonnevilles for the Heat Sink and Zenor Diode setup that Lucas Electrics used to get rid of extra electrical current. I'm not sure but I suppose it would work, but it does get a bit hard in consistenct after some time.



Glenn Stanton

Manager of Training

Burnham Hydronics

U.S. Boiler Co., Inc.

Brad White_16

More a ? of curiosity

it seemed like a valid application, one of several options, Glenn. Thanks. We did specify that setup on V-11's on the Dana Hall job here in MA. After some initial teething it is working well I hear. (By Yvon a beer; he earned one!)

Brad

Robert_15

Glenn

But if i put the supply senser just after the circulator where the two zones branch off it does not seem to read the temp just say i put the boiler aquastat to 200f the boiler would go to 200 without the ODR sensing it. maybe i will try it again. maybe on top of the supply i have a purge valve maybe replace that with some kind of fitting to put the senser

Unknown

I'll do that

I spent quite a bit of time with Yvon over the past few years during the initial development and then introduction of the RTC. I spoke to numerous prominent engineering firms initially about the possible need for boiler protection, then the introduction of the control and finally a series of follow up meetings this past year to ensure that the control systems are performing as intended. he is a great guy and most certainly a hard worker.



Glenn Stanton

Manager of Training

Burnham Hydronics

U.S. Boiler Co., Inc.

Robert_15

brad

Hi Brad i did what you said and it is more accurate. I am going to watch it and see. when the warm weather comes i will see how the odr works now
Thank for your help
Scott

Brad White_17

You are welcome, Scott

Keep us posted on the results, would you? Stay warm,

Brad

Robert_15

Hi Glenn I am going to put the senser in the supply. i do relize that the ideal location would be after the bypass put it would seem to me that the temp. would be much cooler because of the bypass water coming through. i have right now is a tee off the top of the supply (looks like yours)with a purge valve i would replace that with what you have. less then a foot is another tee that has the bypass coming into it then from there it all goes to the system. do you think that would work? Scott

Robert_15

glenn

Ok then i will put it after the bypass. there is a elbow just after the expantion tank but before the circulator would that be ok to put there? the reason is after the circulator the pipe is redused to 3/4 copper i was thinking that the 1 1/2 steel pipe would offer more room for the probe & water flow. if not there is no elbow after the circulator just streight copper pipe before the zones split. if you think it will not i will try to put it after the circulator scott

Robert_15

glenn

this is after the bypass i was thinking of using a 4 way fitting and have the senser facing down towards the circulator and then having the two zones going left & right do think that is better (that is where the senser was at first not there now)
thanks scott

Unknown

Probably not a good idea!

Not that it is a huge issue, but using a cross tee with the immersion well inverted into the top of the tee will leave you with a spot where air can get trapped. I would simply cut in a branch tee either above or below the pump with an extension and female adapter long enough for the end of the immersion well to be in the supply main flow but not quite touching the back of the tee. The branch of the tee can be either 3/4" or 1" to be able to surround the well with water and not trap air. The other problem would be trying to locate a cross tee.



Glenn Stanton

Manager of Training

Burnham Hydronics

U.S. Boiler Co., Inc.

Robert_15

so i will put it just below the circulator there is a elbow there i will change it out. my concern was with the cooler water but it should mix before it reachs the senser
thanks
scott

Robert_15

Glenn

Glenn I have one more question should i have a pipe going from the tee off to the return to insure proper mixing. the return is three feet below the supply where the circulator is. i would put a ball valve there and adjust the flow
Thanks
Scott