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New Boiler can't keep up (13 Posts)
New Boiler can't keep upThe recent cold snap has reminded me that the new Boiler that was installed in 1999 does not heat my house adequately. At 5°F outside, it cannot maintain 65°F inside. The old Boiler did but I don’t know its size or model number. No changes were made to the baseboard fin/tube system. There were 2 zones originally. The old one also supplied DHW. The new one has a separate Phase III indirect hot water heating/holding tank and is heated using a third zone . In 2006, a room was added above the garage and a separate zone was added for BB heat. That makes 4 zones total. In addition, the first floor splits into 3 sections, so there are 3 return line upstream of a single zone valve. Each of these returns includes a FLAIR Super Purge and Balancing Valve (jpg attached or see http://www.flairproducts.net/producthistory.html#superpurge). The second floor splits into 2 sections and no longer has the Flair Valves.
I understand the basics of how the heating system but am not very knowledgable about the details and need your help. Here are the facts regarding my system along with some test results:
House is approx. 4000 sq-ft and 30 miles north of Philadelphia.
Boiler is a Peerless WBV-04 at 178,000/155,000 BTU/Hr, output/rated.
There is one Taco circulator for all 4 zones. I don’t see a model number on it but its powered by a GE 1/12 HP Motor. (I would thing this isn’t a good design as the flow rate will vary by up to a factor of 4 depending how many zones are calling for heat.
Aquastat (Honeywell Model #L7124) is set at 190°/160°/10° for high/low/diff.
Temperature gauge on boiler is 170° when it turns on and it shuts off at just below 190° but the temperature continues to climb to just about 190°F. I’ve read that the lower this temperature, the less heat is lost through the chimney. However, doesn’t a lower temperature of the circulating water reduce the heat output of the baseboards?
The following temperature reading were made with an IR “gun” type thermometer with unknown accuracy.
Discharge temp (with boiler at 190) is 170°F
Return temp (with boiler at 190) is 135°F
On that day, it stayed on for about 5 minutes and circulated for 8 minutes before the boiler turned on again.
Individual returns when main return was about 120°F:
3 (new room above garage): 85°F (probably not calling for heat)
4 DHW: 125°F
I think the FLAIR valves might be contributing to the problem, but the heat on the second floor is not adequate so that’s not the only thing that is wrong.
What suggestions do you have and/or what additional information do you need from me to evaluate this problem?
Also, in the summer, the boiler still cycles on and off 3 or 4 times a day, even when DHW isn’t being used. Is this just to maintain the boiler at 170°F or because the DHW tank temp has dropped to below its 120°F setting and is calling for heat?
Below is the text of FAXes I sent 14 years ago to the company who sold and installed the new bopiler. Much of this text is just a repeat of the above.
Since 2000, it hasn’t gotten as cold so it hasn’t been as much of an issue.
Jan 24, 2000
I am not happy with the new Boiler I purchased from your company last October to replace my 25-year-old Boiler with a top of the line model. However, on 4 or 5 occasions this winter, the house has been colder than it should be. The 3 or 4 service visits all yielded the same results: The serviceman watches the Boiler turn on, the water temperature gauge increase to 205°F (I increased it 5° or 10° at a time from 180° as suggested by your company) and then shut off. Then they check with their hands to see that he radiators are warm. Then they say something like: “There’s nothing wrong with the Boiler. It’s just very cold and you can’t turn back the thermostat and have the house heat up.” I think something is still wrong. When it is cold, the Boiler can’t even hold the set temperature in the house.
I have two Honeywell Model CT3400 Thermostats. They allow for four temperature settings each on weekdays, Saturdays and Sundays. These thermostat record the heating rate and actually call for heat earlier than the set time so the temperature is reached by the set time. In order for these thermostats to work properly, I was instructed to install a relay at each zone valve being controlled. Since installing the new Boiler, I have had to increase the turn-back temperature from as low as 50°F with my old Boiler to 66°F now. Here is an example of how it used to work and how it works now:
When going away for winter weekend’s two years ago (1998), the thermostat was set at 50°F for Saturday and Sunday until 4:30 PM when it changed to 71°F. This 4:30 setting should bring the house to 71°F by 4:30PM. When returning home, the house was 71°F no matter how cold it was outside. This past weekend (in 2000), the turn-back setting was 66°F instead of 50°F. Again it was set to reach 71°F by 4:30 PM. When we arrived home at 7:30 PM the temperature was only 69°F inside with an outside temperature of about 25°F. I think the new Boiler should be able to heat the house to 71°F easily when the outside temperature is seasonable.
Last January (1999), your company replaced a leaky circulator. The new one was much smaller than the old one. The house didn’t heat well at all. I called another company and their service man found that the Boiler set temperature was lowered for the replacement but not returned to the proper limit. He reset it but it didn’t seem to work as well as the old one but I didn’t complain about it.
I remember having my heating system checked while I lived in Massachusetts. Their serviceman used some sort of thermometer to check the temperature of the radiators. Perhaps you need to do that as well to make sure the system is working as efficiently as it should. I expect another visit to make my new system work as well as the old one. I’m not sure exactly how you should check to find what is wrong but here are a few places to start:
The circulator is undersized
The circulator impeller is uncoupled from the motor and all we are getting is natural circulation.
The zone valves are not opening fully.
There is foreign material partially blocking the flow.
The Boiler temperature gauge is inaccurate.
The Thermostats don’t work right for this type of Boiler Control System.
Again, these are just my ideas. I think it is your company’s responsibility to get the new Boiler to work as effectively as the old one.
Jan 28, 200 Fax
Your service man, Rich, visited on Wednesday and installed a larger circulator. Using thermocouples he tested the outlet and return temperatures. There was a significant improvement and I thought the problem had been solved. It hasn’t. The first floor zone was set to be 65° overnight, to rise to 67° by 5:50 AM and 71° by 7:20 AM. At 6:30 it was 63° and by 7:00 AM, with the thermostat calling for heat, the temperature had actually dropped to 62°F. Now, at 10:00 AM it’s only up to 65°F.
Here is what I plan to do next:
Put new batteries in the Thermostats
Increase the Boiler water temperature (the silver wheel in the Honeywell controller indicated 195° but the temperature gauge read 205°F. Perhaps the gauge is not accurate. I have raised the temperature to 205° on the wheel, which give an indicated 215° on the temperature gauge.
Vacuum the radiators to improve air circulation.
Did anyoneever do a heat loss calculation on your house? And, if they did, does the boiler have the capacity to handle that heat loss?
Second question -- does the installed radiation have the capacity to absorb the heat from the boiler?
If the answer to either question is no, there's no point in going any further at this time -- your heating system simply isn't big enough to handle the load.
If the boiler is big enough, however, there is a possibility that there simply isn't enough flow in the radiation to carry the heat. Is this primary/secondary? Straight through?Jamie
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.
Hoffman Equipped System (all original except boiler), Weil-McClain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
Sorry aboutyour bad luck. Maybe we can help.
First, I think you have a (Honeywell Model #L7224 Aquastat. That comes standard with your boiler. I want you to turn the low limit on the controller down to 140° Leave the differentials at 10° for now. After you have it running, redo all the supply and return measurements. Only this time wrap the pipe with a piece of black tape before you take the measurements. Improved accuracy! Record the runtimes of the boiler the way you did before.
Also take some pics. and post them.
Hmmmmm.Along with Jamie's excellent advice, I wonder about few things.
With an indirect, why is the boiler maintaining such a high temp? I think you are controlling the indirect incorrectly, by just having it as a zone.
How did they choose which circ to put in? Maybe a smarter circ, after doing the math, is a better option.
The fact that the boiler is shutting off on high limit may mean the boiler isn't undersized, if all zones are calling.
Are you sure all the air is purged out of the split loops in each zone? Are they properly balanced?
How much pressure in the boiler & how many feet in height from the boiler to the top of the highest piece of radiation?
What kind of controls on the boiler, besides the aquastat?
You added a zone after the boiler was replaced. And this is the coldest winter in this area in about 18 years.
Ideally you may need to pay a hydronics expert to spend as much time as they need to evaluate, measure, calculate & look over the entire system, to make the proper recommendations to get your system working like it should.
Edit: one other thing, 15 years with this boiler, did it ever work properly. Keep in mind your old boiler could have been way oversized, and was able to heat the home quicker.steveThis post was edited by an admin on January 31, 2014 10:09 PM.
Heat Loss:Go out and buy a big box of split foam cell insulation. Cover all the pipes you can get to in whatever spaces you can get to. Before you install the insulation, if you have a really accurate thermometer ( I often use the temperature probe on my true RMS Multi-tester) and measure the temperature of the heat as it leaves the longest run leaving the boiler and at the farthest point before it goes in to a heat emitting unit. If the temperature drop is more than 5 degrees, it really needs to be insulated. Tape the probe to the pipe and cover it with a piece of insulation. The hottest water inside a pipe is in the middle, not the outside edge.
The Peerless Boiler WBV-4 is rated at two outputs. What size nozzle do you have in the burner? Are you on the smaller size for the application? Like under-fired for the lower application? Switch to the minimum nozzle for the lower application or higher. If you can get two True RMS Multi-testers with temperature probes, and they agree with each other, put one on the supply outlet at the boiler and the other on the return. See what they say. Insulate the exposed the pipes. Does the return temperature go up? If it does, that is heat lost and not available to the radiation.
Using clock thermostat (set back thermostats) can be difficult when it gets really cold outside because it is the same as lowering the outside air temperature when you turn up the thermostat.
Your problems are problems that technicians that have the experience can "feel" what is going on. Its an acquired skill. I haven't seen many "normal" houses that a Peerless WBV-4 wouldn't heat.
That boiler, as installed, is rated to fire from .95 GPH to 1.50 GPH. If the burner is fired at .85 GPH, it needs to be bumped up. You need to have someone with digital combustion analysis equipment to bump it up to at least 1.25 GPH while it is cold and see what happens. I think your boiler is under-fired and not putting the needed nuts into your building. You need to pay for a Professional to solve your problems.
You have spent far too much time over analyzing your problem and going down the wrong path. You will confuse and intimidate someone trying to figure out your problems.This post was edited by an admin on January 31, 2014 11:20 PM.
Cant keep upHello ,does your system have a sprio vent installed ? If so have them check the screen used to grab air bubbles . I found several clogged up causing low flow . Replaced the screen and problem was solved
Thanks to allfor your responses. I will perform the suggested tests and post the results and some pix tomorrow.
I know the tech's experimented with the nozzle sizing because there used to be a loud "boom" whenever the boiler shut down. I believe the final choice was 1.25 GPH. This boiler has never been able to heat fast enough. The baseboard design should be adequate since the house heated fairly quickly with the old boiler. I don't turn it back now as low as before to compensate.
My oil company assured me that this boiler would supply enough heat, including the addition and the DHW tank. I was also told that if the boiler couldn't keep up with the heat load, it would run continously.
The tech's purged the air last year after I repaired a leaking pipe. However, there are no air purges in the radiators but there also aren't any noises when the water starts to circulate. I doubt that they are properly balanced, specially in the lines with the Super Purge/Balancing Valve that no one seems to understand how to operate.
If the water tank demands heat, are the other zones supposed to shut off? I don't know if they do or not.
I'd guess the first floor baseboard is about 7 feet above the pump and the second floor is perhaps 16 feet.
As I see it, for this baseboard design only two major changes could have occurred:
1. The temperature of the circulating water
2. The flow rate in the pipe.
If 170°F (and I'll re-check this after putting tape on the pipes) is sufficient
then the flow rate is too low, right? The problem is even is I shut off heat to the addition and the DHW tank, we still don't get enough heat on the first floor. Maybe there is too much restriction through the SuperPurge Valves? Or the new pump is not sized properly?
Pugdad- I do not believe that I have a spiriovent installed in my system, just an air scoop.
Super Purgers:I can't find information from Flair on how those purger's work. From knowledge and experience, I can understand how they work. And it seems that they could be prone to not working as expected. Years ago, I was given some single ones. Their design didn't work well and didn't work well for purging. Is the part on the bottom where you connect a hose and the part on the top turns the paddle/vane. How can you be sure that the Vane is in the perpendicular to the flow position and not interfering with the flow? Is there one of these valves on each return for this zone loop? The design makes me think of lots of turbulence which equals restriction. It almost sounds like they are in a closed position.
Infra-Red thermometer guns can be extremely unreliable until you get used to them. They do not read accurately on copper pipes. Too much reflection. If that is what you are using to get your readings, I find that my hand is more accurate at telling differences in differential. Have you tried to follow the supply through the radiators? Did you check the elements for excessive dust, animal hair and lint? Did you "shoot" that back of the baseboard cabinets to see if they are cold? Lack of insulation will cause the cold to suck heat from the water and fins. Were the baseboards set on a floor and they later added carpet and ran it into the bottom of the baseboards? You need to test it one zone at a time and not ALL zones at once. Take a problem zone. Have the thermostat off. Leave then ALL off. When the supply and return are cold, put your hand on the supply. Hold it somewhat tightly and hold it there until you feel the pipe get warmer. That is the heat from your hand being reflected back. Do the same with the return. Turn on the circulator and feel how hot and fast the pipe gets hot. Follow it along the main for a bit. It should heat as fast or faster than you can walk. Within 15 to 30 seconds from the time the circulator starts, you should be unable to hold your hand on the pipe because it is too hot to hold.
If the heated water going into the first baseboard is hot and as it goes from baseboard to baseboard, it gets cooler, you are either loosing heat in the baseboards or the flow is too low.
If you have a ball valve on the boiler return that will shot off the return flow and a boiler/hose drain above it, IMO, there is NO reason to have those Flair Super Purgers in place. They may be bad but not necessary. I would replace them with ball valves if you need to purge. But ALL purging should be able to be done while standing at the boiler. Old guys like me don't like to run around needlessly.
It sounds like you have a 3 piece Taco 112 circulator. I have seen the impellers come loose and spin, debris has shaved the vanes off the impellor, or the spring coupler is slipping either on the impellor shaft (they leak) or slip on the motor. If there is anything wrong with the bearing bracket or motor, both cost more than a new wet rotor circulator. Replace it with a 3-speed where you can dial in the speed. There's an element of "feel" for these problems. Its an acquired skill.
If you decide that you want to get the purge valves changed, and whomever you find to change them absolutely can not live with eliminating the, use these:
http://www.watts.com/pages/_products_details.asp?pid=7450This post was edited by an admin on February 2, 2014 10:33 AM.
might contributeI didn't think those garbage Flair purge and balance valves still existed. They were popular in the 70's. They were spring loaded, as you rotate the knob, they would become a butterfly valve, then pop open. Often times they wouldn't close
A voice of experience. They were junk. And the regular purgers leaked at the stem after a few years. And leaked out the port.
It's too warm outside to run testsThere is no call for heat so the circulator isn't running much at all so I can't really do the tests. As suggested, I will put tape on the pipes when checking the temperatures. This should make the emmissivity more uniform. (But, last week, I also tried the grab method and found most were too hot to hold for even a second.) Also with the circulator not running, it seemed that the boiler dropped below 170°F before starting. Is that because of the "diff" temp of 10°F? i.e. When the circulator isn't running the boiler doesn't start until its temperature drops below the min of 170° less 10° diff or 160°F? If that's true, then increasing the diff should reduce the cycling in the summer, correct?
I've attached pictures with captions illustrating how everything is piped. It appears that Zones 1, 2, and DHW are all connected to one 2-wire line going to the Aquastat. There is another 2-wire line from the zone valve for the added room that connects to the same terminals inside the Aquastat and has a separate transformer.
Years ago, I added split foam insulation to some of the DHW pipes in the basement but I overlooked the 38 foot long 1 1/4" main header. That should help but still wouldn't explain why the old boiler furnished sufficient heat.
I did not mention that the heating system in the addition is capable of heating the room quickly and maintaining 68°F regardless of the outside temperature. That's probably due to have better (and cleaner) and more baseboards and bypasses the SuperPurge Valves. I will replace these soon.
I thinksomeone was afraid to update everything when they replaced the boiler. A Taco 110 is a great circ, but can't see that it was installed new in 1999, nor the extrol tank, or many of the other things there. The wiring looks like a rat's nest, and a plus would have been to go with fast acting zone valves, get rid of the old Flair valves, and so on. I don't mean to pick your system apart, but sad that there are so called installers out there that charge a lot of $$$ for little to no work or product involved
billtwocaseWe lost power so I haven't been able to do many tests except the firing time was again about 5 minutes. Cooling rate was about 4 minutes as all zones were calling for heat after the power was turned back on.
I have one of those service agreements with my oil company. I believe the Taco pump on the old boiler leaked and they replaced it in 1998. Then, when the house didn't heat fast enough with the new boiler, they brought a bigger, but used pump (you might not be able to observe this from the picture but the pump and motor are different shades of green).
I'll have to accept responsibility for the rat's nest since I was the person who installed the isolating relays.
As for the other equipment, I don't remember what they agreed to include when the replaced the boiler and added the holding tank but most of those things seem to be operating OK except for the FLAIR Valves. I agree that they need to be replaced since we don't really know how they should be adjusted.
Two things I found while reading the Thermostat instructions:
1. If you have hot water baseboard heat and you are using 3-wire zone valves, an isolating relay must be installed. I installed these in the 1990 when I installed these thermostats.
2. If the Boiler cycles too often or not enough, you can adjust the number of cycles per hour. I remember a few times a few years ago when there seemed to be something unusual about the controls (boiler hot enough, a zone calling for heat, but the circulator wasn't running). Perhaps, this cycle restriction could be a cause of my problems?