can't raise supply temp > 155F??

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Old 11-24-08, 09:21 AM
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can't raise supply temp > 155F??

my 9 y/o burnham 3WNH [1.09 gph] oil boiler seems to work ok. the 4 ERIE AG13A02A zone valves seem to work ok. they are one year old, as i replaced the soldered in type valves with the replaceable head type units last year. the honeywell R8182H aquastat [triplestat] was on the boiler when we bought the house.
however, when we bought the house, the system did have a remote water heater controlled by the boiler. i took out that tank and replaced that one with a separate lp tank that works great. i used the zone valve and supply and return stubs that were used for the remote water heater and added the tube/fin baseboards that were used in the new addition. in other words, the old water heater became the new tube/fin baseboards, but nothing else was changed. of course, a new thermostat was added in the new addition to replace the thermostat in the water heater tank.
now, here is my quandry: no matter how i set up the aquastat, i cannot raise the supply temp above 155F. i have a dial type thermometer strapped to 1 1/4 copper pipe that comes out of the boiler, before the manifold, but it never reads higher than about 140; but maybe this is not completely accurate. i have taken hot water [when both the single pump and boiler are both running] from a faucet just 2 feet from the start of boiler outflow and used an infrared temp gun, and the temp is never higher than 155, even if the triple stat settings are 210/185 with the diff set to 25. the strange part is that the round thermometer that comes out of the boiler says that the boiler water is about 210 [at that point], even though the hot water coming from the faucet, 2 feet away, is only 155. how can this be? there is a direct conflict between what the aquastat and boiler gauge say and between the external strapped on pipe gauge and the direct reading of temp from hot water using an IR gun. it is almost as if there is some kind of bypass that adds cool water, after the boiler gauge takes a reading, to lower the temp, but i can see no bypass of any type. i used the IR gun at the some panel radiators and the temp is never higher than about 145. i can never get water into any radiators higher than that temp. all risers and supply pipes are well insulated and none are in exterior walls and the total distance from the boiler to the first radiator is only about 15 feet, of well insulated 3/4 inch supply line. is it voodoo?? am i cursed?? psychotic??
 
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Old 11-24-08, 12:03 PM
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I'd question the strap-on thermometer and the IR thermometer. Using an IR thermometer can be quite tricky. It will NOT read correctly from a copper pipe unless you first paint the pipe with flat black paint where you want to take the reading. Nor is it likely to give an accurate reading pointing to a cup/can/bucket of water.

Are you having trouble heating the house?

If you want a better way to measure the temperatures of the piping then I suggest that you buy one of the digital thermometers for oven (cooking) use that has a probe on a wire. You would need to strap the probe to the pipe using a worm-gear type hose clamp (don't clamp too tightly) and them insulate the probe/pipe with several layers of rags or fiberglass insulation.
 
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Old 11-24-08, 12:54 PM
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in favor of the IR gun, when i point it into a pan of boiling water it reads 212. when i point it at a wall of the house that has a bulb thermometer [red fluid] hanging from it, the IR gun and the thermometer give the same reading. i do believe that the IR gun is accurate. if so, then the hot water coming from the drain, 2 feet from the boiler is about 155, but never higher, no matter what the thermometer on the boiler says, even if it reads as high as 220, while the aquastat is set at 210/180 with the diff at 25. i can heat the house, but i would like a warmer supply temp going to the baseboards. the obvious problem with the low supply temp is that the last baseboard in the circuit gets cool water. the drop in one circuit is from 130 in the first bedroom to about 80 in the last bedroom. this is for a single pipe baseboard system. of course, my myson radiators are piped with risers going up and down from t's from the single line continuing underneath to the next radiator. this keeps the supply more even from first to last radiator. the problem is with single pipe baseboard system running in series.
 
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Old 11-24-08, 06:02 PM
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from 130 in the first bedroom to about 80 in the last bedroom
This differential would suggest either a VERY long run of baseboard, or very low flow in the circuit.

It's not unusual to see differences in the water temp at various points in the boiler ... the point at which the thermometer and the aquastat are mounted could easily be cooler or hotter than the exiting water ... that difference does sound like a lot though...

EMISSIVITY is a term you need to understand when you use an IR thermometer. It can affect the accuracy greatly. Some $$$ ones have a setting for emissivity. I have found steel and cast iron to be very close to the actual water temp. Copper... not so ... don't trust a reading on copper unless you do the flat black paint trick that furd recommended. In fact, if you paint all the spots you want to measure flat black, you guarantee at least that the differences between them will be fairly close ...

Is there a manual for that boiler on the web ?

Does the return come in the bottom and the supply out the top, with the controls at the other end of the boiler ?
 
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Old 11-24-08, 06:37 PM
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Yesw trooper it is a V7 boiler. It may be the location. I would also get a different thermometer.
 
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Old 11-25-08, 07:45 AM
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i measured the temp of the hot water DIRECTLY [not the pipes themselves] as i ran some hot water into a small bucket from a faucet that i plumbed into the system about 2 feet from the boiler. emmisivity is not an issue. i aimed the IR gun at the surface of the hot water only a second after opening the faucet. at that time the boiler gauge read about 220 degrees, and the IR gun about 155. this is why i am going crazy. i know the gun is accurate from independent tests.
the return is at the bottom rear of the boiler and that is where the circulator is. the supply is at the top front. the only thing between the start of the supply and the faucet i am using is a microbubbler separator and a diaphragm type expansion tank. still, the faucet is only about 2-3 feet from the start of the supply. i am contacting burnham for an installion booklet for this boiler, but have heard nothing back. the circulator is a single standard bell and gossett but i don't have the model number due to corrosion. however, basd on net research, it is the common home owner type and should be adequate to give flow in this system. actually, i quickly get hot water to all circuits on a call for heat. hwoever, the water is not as hot as it ought to be, so circulator capacity does not seem to be an issue. ALL heating pipes, even in the walls, are well insulated.
i have 2 circuits of flat panel radiators supplied by a single pipe using monoflo t's. the other 2 circuits are baseboards, single pipe. the lenght of the longest circuit [baseboard] is about 115-125 feet, by my estimate.
 
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Old 11-25-08, 03:40 PM
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Is there an extra 3/4" tapping in the boiler very close to where the aquastat is mounted ? If so, why not install a well there ? Get a direct measurement from right there... see how that compares to the a'stat control ...

Waitaminnit... the temp gauge on the boiler is right there ... why not change that out ? Don't neglect coincidence ... it is possible that both the thermometer and the aquastat are 'off' ... (unlikely, yes, but how else would you verify ?) So, the least $ way is probably the thermostat ...

I didn't mean to suggest that the problem you have is low flow ... that would be secondary to the temp problem ... but, here's the thing ... let's just theorize that you did have low flow in the system ... there's evidence to that fact ... you stated 130 into the run of baseboard, and 80 out ... that water would HAVE to be moving mighty slowly to give up that much heat, OR, you have way too much baseboard on one 3/4" run ...

On with the theory ... if you have low flow in the system, then you must have low flow through the boiler ... with low flow through the boiler, you have no guarantee that the water is going to flow through the boiler via the route that the manufacturer designed. You could have some hot spots ... and maybe the aquastat is mounted in one of those hot spots ... with not enough flow through the boiler, the water might not completely 'scour' the heat out ...

just a thought ...

That 115-125 run ... how much of that is actually fin-tube element ? and I'll assume the rest is interconnecting piping?
 
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Old 11-25-08, 05:02 PM
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I once had a problem similar to what you are experiencing. I found that the probe from the aquastat wasn't all the way inside the well and wasn't reading the boiler temp accurately.

If you think that the R8182H triple aquastat may be reading the boiler temp inaccurately, remove it and try reinstalling it making sure that the probe going into the well has conductive grease on it and that it goes all the way into the well and is making contact with the inside surface of the well. Just a suggestion.

Also, pertaining to your flow issue the circulator on the system may be sized right but the impeller may have a defect/damage and this will certainly hurt the flow especially on a long run.
 
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Old 11-25-08, 05:47 PM
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I'll agree that low flow is a distinct possibility. More likely as not the aquastat thermowell is located close to and above the firebox and may indeed be "seeing" higher temperatures than the boiler thermometer and especially the outlet piping.

How about some pictures of the boiler and near piping?
 
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Old 11-26-08, 08:04 AM
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the total length of the tube/fin is about 46 feet [8 for study; 6and 6 for outer walls of bedroom; 6 for outer wall bathroom, 6 and 6 for outer walls bedroom; 8 for outer wall bedroom] with about 65-75 feet total supply and return lines. this is an estimate, but i am not that far off. i am intrigued by the low flow suggestions. i think the b and g pump is the s-100. it seems older than the 9 y/o boiler [the date of boiler installation is written on the unit], as does the aquastat. this is only eyeball, but the metal of the boiler seems pretty good, but the pump is somewhat corroded [with no leaks anywhere] and the aquastat [which also looks dull and old] is actually labeled simply as a honeywell R8182 with no following letter on the label. the features and dial setup are those of an R8182 H series, but the H is supposed to be mounted away from the boiler, while my aquastat is mounted directly onto the boiler; kind of a directly mounted "H". i know the prior owner was a litrtle short of money, and it is esay to imagine he re-used the same circulator and aquastat from the old unit he replaced.
if i decided to replace the circulator, i understand the taco-7 is a direct bolt [same flanges] on with no need to drain the system. am i correct? also, i think the taco-8 delivers a higher flow rate at the same head pressure. any thoughts on that?? also, is the taco-8 a direct bolt on, or do i have to drain the system and diddle with the flanges for either taco circualtor?? i think low flow might be the culprit and i am willing to replace the old circulator to find out, if it is not a major drain boiler job in the middle of a wisconsin winter [i could see a corroded impellor given our hard well water]. finally, if necessary to replace the boiler temp/pressure probe, do i have to drain the system to replace that???
happy thanksgiving to all and thanks for the attention to my confusing problem.
fuinally, maybe i will get a digital camera one of these days so that i can post pictures. i really ought to join the 20th century at last [that was a joke].
 
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Old 11-26-08, 03:52 PM
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I've gotta question that 50 degree diff ... and suggest that you retake the measurements on the temp in and out of that loop ... it seems almost impossible that your flow could be so slow as to lose 1 degree per foot of fin tube ...

If you don't want to paint a spot on the pipes, try black electrical tape ... one thing I know for certain, an IR gun works for nuthin' on copper pipe ...

with no need to drain the system. am i correct?
Partially... the 007 I believe is a direct bolt in ... but unless you have service valves on each end of the circulator, you will have to at least partially drain the system. But, don't be so quick to change that circ just yet ...

Re-do the temp measurements first ... they are suspect ...

boiler temp/pressure probe, do i have to drain the system to replace that?
Usually... I've seen wells that have a 'valve' on the bottom that closes when you unscrew the gauge, but they only work when new ... and even then you at least should drop the pressure to zero by draining a little water ... but in general, yes. If you can work fast, you could probably drop pressure to zero, unscrew the old ... then, real quick pull and stick the new one ... but keep a box of pampers close by, cuz you will lose some water ... cover the burner and any controls with a plastic sheet ...

Look at your system piping ... are there any valves that you can close to isolate sections and prevent having to drain them? The less you drain the better ...

Pics would be nice ... and I got the joke! ... sounds like my 'day job' ... I swear some of the 'test stands' still have 386 computers on them ! Welcome to the 20th century! ha!
 
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Old 11-29-08, 09:22 AM
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you put a spear in my chest [that was a joke] with the comment about the 386 microprocessor. i am using my wife's computer now, but mine, upstairs, still runs windows 95 with a 386 processor. has it been that long.......?

anyway, 3 quick questions:

how many thermostats [round honeywells] can run off of one 24 volt transformer [i have 4]

how many zone valves can run off the R8182H aquastat [i have 4]

is 1.2 feet per second flow through the loop too slow [i think it is]

thanks for the help
 
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Old 11-29-08, 02:20 PM
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Fear not Doc, you are not alone! I've got more than a few computers around here that are older than most of the ppl on the internet! One of each as a matter of fact... every OS from 3.1 on up ... 95,98,ME,XP,(no vista!)... and one that still runs only DOS (5.0), one that even runs TRSDOS (MIII) and several even older ... but I digress.

It's not so much how many thermostats, but rather how many zone valves. It depends... (doesn't it always?) ... on the type of zone valve, and the actual capacity of the transformer. You need to look up the VA spec on the zone valves, then adding them all up (worst case all calling same time), make sure they don't exceed the rating of your transformer (typically 40 VA). That VA is the 'number to compare'... if it's a 40 VA transformer, you may have one too many on the line ... but as long as they never all call at the same time, you'll be OK ... funny thing is, it's always the coldest night of the year when they all call at 3 AM ... in a blizzard state of emergency ... on a Sunday night Christmas Eve... and THAT's when the transformer gives up it's ghost. So check out the specs to be sure yer OK ...

I THINK (not sure, don't hold me to it ...) that the 8182 can only safely run THREE zone valves ... but, that's ONLY if they are running on the internal transformer in the 8182 ... if you've got an external transformer, it's a good chance they are wired two and two ... in which case you would be fine ... you would need to verify by tracing out the wiring ...

Yeah, 1.2 FPS is a little slow ... usually between 2 and 4 FPS is good ... not too slow to let air be a problem ... and not too fast for noise ... if it's too slow, the water starts runnin' outta heat for the end of the line radiators ... water cools too much before it gets there.

BUT, I don't even think 1.2 FPS is slow enough for a fifty degree diff ...
 
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Old 11-30-08, 04:36 AM
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i looked for the "VA" but could find nothing that looked like that. the zone valve is an erie 13AO2A pop top.
the numbers on the label are:
9-24 v dc 100 ma
24-240 v ac 10 ma
5a end switch
can i calculate VA from this???

i will replace [next summer] the circulator with a taco 007 or 008 after i talk to the friendly folks at houseneeds. always helpful in the past.

finally, most of my heating problems are solved. the short cycling and the low supply temp are a thing of the past.

i reset the aquastat to 200 over 120, diff 25.

my wife and i spent a few hours testing each zone separately by turning down the heat call on the other three stats.

on each stat i raised the anticipator from the 200 ma suggested by honeywell for their R8182 to the 400 ma suggested by myself. i figured this would cause the thermostat to call for more heat prolonging the boiler cycle time. in fact, this worked. the average flame time is now about 3-4 minutes, up from 1 minute [more fuel efficient and better for chimney]. the supply temp is up to 175 to 180, up from 155, which gives more heat to the last radiator in the loop. for personal reasons we always keep the stats set at 62 in all zones. the rooms are now always between a low of 62 and a high of 64 with less frequent but longer calls for heat, and a gradual cooldown in between. i don't even notice the change it is so gradual. all in all i am over the moon!

i want to thank you for all of the help and for the pleasant humor. its nice to know there are good people "out there."
 
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