Hey Kids,

I have a Burnam series V-15A-T with a R8182D aquastat. I have two questions. First, the combination water temperature/pressure gauge on the front of the unit; is that the temp. of the water out or the return?

My system has four zones, three of which actuate Taco 007 pumps via Honeywell RA-89A thermostat controllers. The remaining zone thermostat is wired directly to the aquastat and when it calls for heat, the boiler comes on for as long as it takes to either satisfy the thermostat or reach the upper set point. And controls the fourth circulating pump. Standard stuff.

However, I also have an outdoor wood-fired water boiler that is integrated into the system which heats that same water via a heat exchanger. If the heat exchanger cannot keep up with the demand of the baseboard radiators the boiler ignites when the water temp. reaches the low setting.

Can I disconnect the thermostat from the aquastat and run that fourth pump with another one of the aforementioned controllers? I mean, of course I can, but will the oil burner function normally with regard to the upper/lower set points? I don't want the oil burner igniting every time that thermostat calls for heat, but come on and shut off as a function of the set-points when required.

Thanks guys,

G

 

Hi Gramps,

That aquastat has two temperature ranges.
One set maintains the temperture when there is no call for heat.
The other set maintains a high limit temperature when there is a heat call.
If you disconnect the 4th thermostat, the boiler will cycle at the lower settings.

What are all the dials on the aquastat set to?


Typially the gauge reads at the middle or top of a boiler, thus it would more closely reflect the supply temps, not the return.

Peter

 

Hey Gary, do I see a "Touch of Gray" there ?

Isn't this kinda a good thing ? If the wood stove can't heat the house, then the backup automatically kicks in ?

Or does the wood boiler eventually 'catch up' ?

I'm not familiar with this model... is it old?

 

Does this boiler also provide domestic hot water to the home? Is that the reason that you have a 'triple' aquastat installed?

 

For anyone interested, the literature for this aquastat is here: customer.honeywell.com/techlit/pdf/68-0000s/68-0105.pdf

With regard to the temperature settings: I usually keep the low limit low ~120, and the upper limit low ~140, differential 10. Just so as to give the system a little bump when the heat exchanger cannot keep up, which may occur when the outside temperature <15 degrees and multiple zones are calling for heat. That issue is also being worked on, I contend that the heat exchanger is undersized for the house.

Let me see if I understand what this all means...if the thermostat does not call for heat then as long as the water on the house side of the heat exchanger remains above 110 the oil burner should not come on. If the water drops below 110 then the burner ignites and remains on until the water reaches 120 and shuts off. If the thermostat calls for heat and the water is below 140 the burner ignites and remains on till the water reaches 140 or the thermostat is satisfied. If the thermostat is not satisfied by the time the water drops to 130, the boiler kicks back on. Or does the circulator continue to run till the lo set point, at which time the pump stops and the burner starts? The former seems to make more sense. Speaking independently of the remaining three zones, which would affect the operation of the burner based on the lo setting. Yes?

The boiler can provide, and did at one time, provide the domestic hot water. The system has been piped/valved to bypass that feature and the domestic hot water is provided by an 80 gal electric tank that has a water jacket heat exchanger incorporated so as the have the wood boiler heat the domestic hot water during the heating season (I shut the breaker off). So the aquastat is designed to maintain the domestic hot water also, using the lo setting.

According to the Burnham "Installation and Operating Instructions" this unit originally came with a L8124C aquastat and R4184D burner control.

I bought the house with this system already installed, and yes, it is kind of old. The house was built in 1991 and the wood fired boiler added in 1997. I tend to think the oil burner is original to the house. And yes, it is a good thing....seamless integration. However, I find the boiler igniting every time that thermostat calls for heat annoying and a waste of resources.

So based on the above, and the comment by Peter, then disconnecting the fourth thermostat from the 8182 and running it with a separate controller, like the others, is just what I am looking to achieve...Yes..No?

Thanks guys for your input and patience!!

Gary

 

Correct.

Correct. ALSO, when the boiler drops below 110 the CIRCULATOR will be DISABLED. Once the control bounces off the bottom limit, the circ will not run again until the boiler hits the LOW setpoint.

Correct. And if this call for heat occurs after the boiler has bounced off the LO - DIFF, and is recovering toward 120, but not there yet, the circ will not run. Once the boiler passes 120, the circ will start and the burner will continue to fire as per your scenario.

Call it the BURNER not the boiler, more specific... Yes, that's correct.

No... that would only happen if the boiler cooled at the onset of a heat call... i.e. say the boiler is sitting at 115 and there's a heat call. The cool water coming back to the boiler cools it that extra 5 degrees and it hits 110 before burner can catch up... THEN the burner will continue to fire but the pump will stop until the boiler recovers to 120.

I think no... Since those other controllers are not signalling the boiler to fire, then if you did that, moving the other one off would mean that NONE of them would ever call the burner to fire.

If you were running on oil, the hottest water you would ever be able get to heat your home would be 120... it would never fire up to high limit... WHICH BY THE WAY IS QUITE A LOW SETTING!

 

Does this mean that the 'other' three zones do NOT call the boiler to fire up the burner?

You might want to re-think that setup a bit.

 

I presume that you have constant circulation on the wood side of the heat exchanger?

Ya know what I would do? I would pull out those 89s, replace with a Taco SR-504 and wire all four thermostats to it... take the pump wiring from the boiler aquastat and run it off the 504.

The endswitch of the 504 would go to the T T terminals of the 8182.

So now you have a system where all four thermostats would call to the boiler for heat and also run their own pump.

Next step is to mod the aquastat to run as a COLD START and NOT maintain a low temp in the boiler. I'll give ya a hint... it's easy... and it's in that product manual you linked to... it's just one step, and it's on page 4. It starts like this... "1. REMOVE RED AND WHITE"

Another hint... to release those wires, ya see that little slot next to where they are plugged in? Got a small flat blade screwdriver? ...

This single step will convert your aquastat to cold-start.

Since all the zones will now call for heat and also run their own pump, there's no need to keep the boiler warm all the time.

 

The last thing would be to set up a strap on aquastat on the pipe from the wood boiler (or even right on the heat exchanger somehow) that would sense when the wood boiler was HOT... and use the contacts from that to signal the burner to NOT fire on a heat call, but the pumps would still run when the thermostat called for heat.

Someone found a neat Ranco control that is just the ticket for this... who was that? Rockledge?

You would wire this control IN SERIES with the wires from the 504 endswitch to the T T on the boiler.

When the wood stove was hot, it would disable the heat call to the boiler by opening the switch... all automatic like.

 

I can't imagine why someone would swap out the more modern aquastat and separate primary control and put in the (more expensive) 8182 ... not only does the thing cost a lot more, what happens when something breaks? Now ya gotta spend MORE money rather than just replace one or the other...

If it were mine... when the 8182 finally bit the dust, I would replace with 'separates'... probably an L7224U and the latest primary control...

 

About that 140 HIGH setting... it really is kinda low... I wouldn't run an oiler any lower than 150 on the HIGH setting, and that is only if you have enough radiation in the home to heat with water that cool.

Google the term "flue gas condensation" then decide if you wish to continue to run it that low.

 

Wow, that's a lot to digest.

Does this mean that the 'other' three zones do NOT call the boiler to fire up the burner?

That is correct. And there is constant circulation on the wood fired side. When everything is running correctly, the water temp leaving the wood fired boiler is ~180, travels underground 200 ft to the house and arrives at ~170, leaves on the return leg ~160. The water leaving the heat exchanger to the radiators is usually ~160. These last two 160's, to some extent, a function of the outside temp and how many zones are calling for heat. Because the extent to which the heat exchanger heats the radiator water has diminished over time (suggesting perhaps a buildup that restricts flow, impedes heat transfer, or both) the water leaving the heat exchanger to the radiators no longer reaches 160 and I'm lucky if it reaches 150. If zones call for heat, that number plummets and the burner kicks on.

So, I'm really dealing with two fundamentally independent issues that become related depending on aforementioned parameters. If I get the heat exchanger issue resolved, the burner should almost never ignite (depending on where I set the lo setting). The water in the system used to never (almost) fall below 130 and heated the house just fine. That's why the low set points, the system used to only need a little temp bump while the heat exchanger caught up.

So, since when everything is working correctly I rarely need the burner to kick on, is the reason I don't want it to kick on because this one thermostat calls for heat. Since the water on both sides is always hot (in theory) because of the circulating pumps (not the ones for the zones) on both sides of the heat exchanger, I don't want the thermostats to fire the burner, just start the individual zone circulators. And have the burner kick on if the water falls below some reasonable threshold temp. I'm ok with the zone circulators running longer to satisfy demand since the radiator temp is lower than it would be if the oil burner was conventionally on-line. It's still much cheaper than burning oil. If after having it my way, it doesn't work as how I envision it should, I can always go back to the current configuration. Of course, the object is to get off the oil. That I still own some oil co. stock just means the rest of you should use it. lol.

I like your cold start idea. The wood side, in effect, is equivalent to maintaining temp on the oil burner side since it is always heating that water, by virtue of a constant circulation pump through the heat exchanger. Which I suppose could also be wired to be cold start.

And the strap on aquastat, that scenario describes what I'm trying to achieve. That wood side water is always HOT. In fact, before I piped in a tempering valve, my domestic hot water at the tap was close to 170. It's consistent with your question about why the swap...who knows what these people were thinking. The liability issue associated with having 170 degree water coming out the tap alone is enough to indicate someones lack of sanity...

I'll give all of this some thought and when I finish dicking around will report on the results. In the mean time, it appears that you have answered my questions and offered some excellent options to contemplate.

Can't thank you enough. And, btw, I had called Burnham and they gave me the high hat (a depression era term for getting dissed), which just goes to show how important/informative the DIY forums are. Screw Burnham.

Gary

 

Are you saying that you have circulation at all times on the boiler side of the heat exchanger also?

Tell me a little more about how this is set up.

Where in the boiler system is the heat exchanger plumbed?

What is the path of the water flow on the boiler side when there are no zones calling for heat? Just through the boiler itself?

You should have a higher delta T across that heat exchanger... so you may well be correct that it is undersized... but on the other hand, if there is not enough (or no) delta across the boiler side, it could mean that flow is lacking there also... or as you suggest, it's getting 'limed up' inside.

Have you considered a buffer tank application? Storing some of that heat for when the zones call. If you had 40 or 50 gallons of water sitting at 180...

Does the wood boiler have controls on it to cut back the fire when the load drops off? an automatic damper? what make/model you have?

 

Yes, there is a B&G PL36 pump on the boiler side always circulating the water through the oil fired boiler.

The set-up is really quite simple. Hot water from the wood boiler (Central Boiler Classic CL5648SB, where the firebox is 56x48in) comes into the house, travels 10 ft to the water jacket (pipe in pipe) heat exchanger on the electric water tank, to the honeycomb heat exchanger and back to the wood fired boiler. That side of the system contains ~400gal of water (I think).

The water in the oil furnace is constantly circulated through the honeycomb, which is attached to the wall right next to the oil furnace. Which raises another design flaw. When the oil burner heats the water higher than the heat exchanger is, I'm now heating the wood side water instead of vice versa.

There is a substantial delta across the heat exchanger for the house side water. If a cold zone calls for heat, once the water begins to circulate (and it is quite cold) the house side water drops considerably in temperature initially and then rises until steady state is achieved. And it's that considerable drop that leads me to believe the exchanger is undersized. Steady state temp during a heat cycle could be higher also. The wood side does not deviate much since there is 400 gal (c x m x deltaT).

The buffer tank concept is also a good idea.

The wood boiler does have a temperature controlled damper.

I opened a Flickr account and uploaded some photos of the system, they can be viewed here.

Heating System - a set on Flickr

 

Gary, I think that maybe the boiler side constant circ pump is a MONSTER of a pump! and probably too big for the purpose. It's very likely that you are pumping WAY too much flow through that heat exchanger and boiler.

I have a few more questions that the pics might answer.

I'm going to look at the pics now...

 

Gary, when was the last time you had the oil burner serviced, and the boiler cleaned?

You should NOT have that much soot! That thing is not running well at all... a sick puppy.

You should NOT have those black soot streaks down the side of the boiler flue pipe... and it looks as though the barometric damper is coated with soot also. Is the power venter properly installed, and working properly? i.e. the boiler will NOT turn on until the power venter operation is proved...

That soot could mean a potential hazardous condition in your home. Where there's soot, there's Carbon Monoxide, and it appears to me that you've got flue gases entering the home... look at those streaks... see how it tells that the flue gas is coming OUT of the pipe?

PLEASE! MAKE SURE YOUR CO DETECTORS ARE FUNCTIONAL! DON'T NEGLECT THIS!

 

Those air vents on the elbows... pointless... in order for those things to work, there has to be someplace underneath them that will collect air. They won't collect any air out of the stream of water rushing past them... just so ya know, if one starts leaking, there's no point in replacing it, just shut the vent and fuggedaboudit.

 

OK, I'm officially envious... dang that's a nice spread ya got! Is that your rack-body? Or is that a delivery?

What are the dimensions of the BRAZED PLATE HEAT EXCANGER ? (hereafter called HX) Are there any manufacturer numbers on it? I'm curious as to it's capacity. Are those 1" piping connections?

What pump is pumping the loop from the stove to the HX ?

 

Is the SHELL AND TUBE HEAT EXCHANGER on the water heater 'home made' can ya tell? I've got some bigazz 2" pipe... I wuz thinking about building one myself...

What size is the outer, and the inner, pipe?

 

Really... that pump is way too big... you are probably pumping that loop at like 25 GPM.

I can't see how or where the loop is tied into the boiler... howizzit?

 

That chimney free-standing? Ain't afraid of wind blowing it over?

 

BTW, I'm Gary.

The soot was there when I got there. Prior residents were a little lax on maintenance. I have the unit serviced annually and, in fact, they're coming this AM. As for those vents, whaddya gonna to do!?

The HX is a B&G model #BP 412-20 (for 20 plates) and is 12 X 4 X 2 in. That's 1 in PEX. The wood side pump is out at the boiler. Actually there are two, the barn has a 900 sq ft shop in it that is also heated (forced air) by the wood boiler. It's toasty warm. Those pumps used to be PL 36's and when they wore out I replaced them with Taco 014's.

That's not my truck, a delivery. These days I get tri-axle loads.

The shell and tube HX is a stock item from the Central Boiler catalog, 1 1/2 in OD, inner tube 3/4 in. I don't know the reasoning behind the large pump on the house side, but that's the one that is called for. Once I've gotten the HX issue cleared up and I speak with the HX distributor again, I'll ask. When I piped in that tempering valve I used an excessive amount of solder and some may well have found it's way the the HX. So much for trying to solder when the water is dripping.

I'll be taking the HX out, doing a little flushing, reassemble then reassess it's performance. These things are not cheap. 412-20 = $570.

The gray PEX is the house side. See behind #5. The gray pipe is attached to a pipe going into the boiler. The return comes out of the boiler at the bottom rear, not evident in the photos.

The oil burner guy just left. His assertion was that irrespective of the thermostat call for heat, the aquastat will maintain water temp between the lo set and high set. That is, the temperature will cycle between the two set points as a temperature maintenance function. He asserts that the two settings are not independent of one another. That's not right, right?

Oh, if you look closely you can see the wire holding up the stack.

Gary

 

I've had a chance to take a closer look at your suggestion regarding the Taco SR504. Let's say, for example, that I used this unit for the three thermostats currently wired to those 89's, and didn't use the end switch. Wouldn't that be equivalent to the current set-up? And if so, why on earth would someone use the 89's in the first place? Is there an advantage of some sort to the 89's.

With regard to cold start, if I remove the leads and wire-nut them together, in the 8182 cover it says that will eliminate the lo limit function and the circulator will run when the thermostat calls for heat. Will the burner fire when the thermostat calls for heat, and then be controlled by the hi setting. And if so, would that mean that the hi setting would be met, the burner shuts off...and if the thermostat has not been satisfied by the time the water temp drops 10 degrees below the hi setting, the burner will come back on? We're assuming the current configuration, and if the 504 were in play with all four wired to it and the end switch to TT...the same thing?

I'm looking at some strap-on aquastats, they're quite readily available.

I think that when it's all said and done my system will be super bad and all the boys will be jealous. I have visions of an adequate HX, reservoir, 504, strap on, etc. dancing in my head...kind of like, well, sugar plums.

 

No, absolutely not. He has no clue how a triple aquastat works.

Yes, they certainly ARE independent functions. Take a look at the schematic if you want further verification.

http://customer.honeywell.com/techli...0s/68-0105.pdf

more later...

 

Yes, it would.

Couldn't tell ya! Why wouldn't one want the boiler to fire when the zone called for heat? Of course when the central is running, you of course don't want the boiler to fire, but what about when you WANT to run the burner? You have no way of doing that.

Better I say to set up the indoor boiler to fire up and run as a 'stand alone' when necessary, and automatically disable the burner when the outdoor boiler is running.

Yes.

Yes.

Yes.

Yum!

 

That's a list price by the way...

50 GPM eh? That is some extremely fast moving water in a 1" pipe! I can't really imagine how that is even possible. A 'normal' flow in 1" tubing in a heating system is only about 8 GPM or so...

I know that the flow rules for HXs are significantly different than normal piping... but still seems like a lot.

Have you ever measured the delta T between the in/out on both circuits? That would be the best indication of how well it's performing.

 

I haven't been able to find much in the way of specs on that HX... everything I've found says to contact your local rep... but what I did find seemed to indicate that this wasn't too far out of line.

 

I put in a call to my local rep, Syracuse Thermal, and the person to whom I should speak was out today. I'll see if I can speak with him tomorrow. I measured the WFB loop again today. It is 430 ft., 410 ft. of which is outside buried underground. Now I wonder if the Taco 014 is sufficient for that length loop. I'll hopefully find out more tomorrow.

With regard to any temperature measurements, the system never has a chance to reach anything like steady-state before the oil burner kicks on. A cold zone calls for heat and the temperature drops like a stone and on comes the burner. Previously I tried measuring temps with an IR thermometer, placing blue tape where I took readings but they were all over the map and I wouldn't rely on them.

I'm looking into more sophisticated temp monitoring systems that can log data.

 

That's one direction? So the total length of tubing to and from the wood to the oil is 860 feet?

And you said it's all one inch, right?

You may be right about the 14 not being enough pump.

 

No, total 430, 205 each way outside and ~20 ft. inside.

 

OK, that's better... I think the 14 might be OK... just guessing after a quick look at the pump curve.

 

Accoding to my handy dandy HDS:
100 feet of 1" pex tubing at 7.5 gallon per minute
is moving at 4 feet per second
has a 3 psi loss or 7 feet of head.

times 430 that works out to 12.9 lbs of pressure loss or
30.2 feet of head.

Not Good.

The Taco 0014 can only do 1 gpm at 22 ft of head.
Very, - not good.

A 0013 might be a far better match and might do about 7+ gpm.



BUT the real question..
How much heat is being lost into the ground ?????

Half is my guess.
Depending on the insulation of course....



Peter

 

Ah, the 0014 is probably moving about 5.5 gpm, depending on the loss thru the exchanger.

Peter

 

Id love to be able to monitor like this dude..
OurCoolHouse

 

I have that system Dave.
It is great. I have a lot of fun with it.
Bit costly, but worth it for sure.

For DIY stuff chck into Arduinio's.

Also Hobo's,
Temperature Data Loggers & Sensors - Onset
but i think the WEL is a better deal.

Peter

 

Yeah... I agree... I did a calc using a Total Equivalent Length of 500' ... figuring that might be close to the loss in the exchanger, and I came up with less than 5 ... the curve is so steep it's hard to get closer than to say it's between 4 and 5 GPM.

So, no, the 14 is not enough pump. The PL36 that was there originally might have been enough...

What if you swapped the 36 on the boiler side with the 14 at the woody?

 

According to the info i have. the PL 36, should give about 7.5 gpm at 33.5 ft, thru 500 ft of 1 inch pex., right at 4 ft per second.

Bingo.

With a 30 DT, that's about 112,500 btu's




Peter

 

Cost is no object. All right, that's a lie.

 

Are you sure we're talking about the same pump? The specs I have seen for the 36 indicate a 40 GPM max.

What does 30 DT mean?

And would swapping the 014 at the boiler for the 36 in the basement do the job? There seems to be a difference of opinion. Also, I will be switching that 20 plate HX for a, probably, 70 plate.

Oh, and by the way...you guys are the best.

G

 

It may be 40 GPM max but pumping up into a 33.5 foot 1 inch pipe, it is only going to shoot out 7 1/2 gallons per minute.
I see in my other post i typo'd the decimal point and it looks like 75, oops.



30DT
Means a 30 degrees difference, or delta, between the supply and return temperatures.

I'd like to know the temperature difference, between the supply at the wood boiler and how much cooler it is when it gets into the cellar...
?????
Ahy idea how mcuh insulation is on the underground pips?


Peter