problem with low-mass boiler

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  #1  
Old 01-19-05, 09:49 AM
jthompvt
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Angry problem with low-mass boiler

I had a System 2000 low-mass boiler installed over the summer. It replaced an OLD cast iron boiler that usually kept our house warm, but ate a LOT of oil and was beginning to be maintenance intensive.

Living in northern VT near the Canadian border, we get some cold weather. In the two cold snaps we've had thus far (meaning 0 degrees or colder), we cannot get the indoor thermostats to read above 62 degrees despite being set to 72. Our house is an old post and beam brick farm house, but has new vinyl replacement windows with insulating glass. We've attempted to winterize all we could without major bucks over the summer.

We have four zones connected to the boiler. Basement unit heater, first floor fin tube, second floor fin tube, and third floor (finished attic) with radiators. All told about 3000 s.f.. The boiler has one circulator TACO 010 and control valves for each zone. The delivery water temp is set now at about 160 or 170 - cannot remember which.

The tech who installed it all came out and told us that our (pre-existing) baseboard fins are installed rotated 90 degrees from where it should be, so that the gap between fins is closed off at top and bottom instead of being on the vertical edges, and that this could cause the ambient temp to be 10 degrees different. Could that be true? Another tech disputed that, and felt that maybe a degree or two might be realistic, but the fins were still hot, so they should still create a decent amount of convection.

On the control panel, the first and second floor zones appear to ALWAYS be in demand. I would expect that because of that the boiler would be in virtually a continual state of operation (firing.) It does fire frequently (maybe every 5 minutes) leading me to beleive there's some kind of bottleneck preventing the hot water from getting into the zones, though I can't imagine what.

I'm not sure how many BTUh's the system is currently designed to deliver, i.e. which nozzle. I think it was around 200,000.

Does anyone have an opinion on these issues, or on low-mass boilers in cold climates in general? I spent a LOT of money on this thing, and so far I'm not happy!
 
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Old 01-19-05, 07:35 PM
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The baseboard element problem is the big killer there. I have dealt with this one before. I hope it was the installers first day on earth because it doesn't take a rocket scientist to see how it SHOULD be installed. Here is an example of how much difference it would make to turn the element. Regular baseboard gives off about 570 btus per foot with 180 degree water in it. If you get hi capacity baseboard, the element is exactly the same but the enclosure is about 2" taller to create more 'convection'. That baseboard gives off about 720 btus per foot with 180 degree water. A slight increase in airflow over the same element increases the output by almost 30%. You have no airflow at all. You will be absolutely amazed at the difference when you get that problem corrected. And you are right that the boiler is bouncing off of high limit all the time because it can never reach the setpoint. That means more wasted heat up the chimney. Go ahead and get the baseboard corrected. It shouldn't be a major operation.

Ken
 
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Old 01-20-05, 09:07 AM
jthompvt
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Ken: Thanks for that input...it's hard to know who's right in things... Most of the baseboard is regular efficiency - one room has high efficiency. The baseboard was all existing when we bought the house, so I can't fault the boiler people there. A little of it is Suntemp brand, but some was Mini-7? Not sure of the name. The friend who looked it over told me with a good leather glove and a soft hand I could rotate the Mini-7 fins myself since they aren't fastened as tightly to the copper as the Suntemp. Do you agree?

Why would the boiler keep bumping up to the high limit? It only holds 5 gallons, so I can understand why it happens frequently, but with a circulator pumping and valve open, I would expect the constant flow of water to moderate the temperature of the water in the chamber since it's always being replaced with cooler. With the baseboard problem, if the demand is always there, is the problem that the fins are not disippating enough heat from the water, so it's return temp is too high?
 
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Old 01-20-05, 09:55 AM
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You could try rotating the fins. It is probably possible. If it was me, I would drain that zone and unsolder the ends and turn the whole element. But that's just me.
The example I gave was to show how a small increase in the 'chimney effect' would increase the outpit by almost 30%. The additional few inches of height of the enclosure creates more airflow over the element (you now have none at all) and takes that much more heat out of the water. In your case, you may as well have straight copper and possibly, yours is no better than an insulated copper pipe running through the room. I hope you can see how emphatic I am about this repair. You still seemed confused about why the boiler is off on high limit. It is because NO heat is being removed from the water in your baseboard. Normally there is about a 10 degree drop as the water goes through the baseboard and can be as much as 20 from one end of a loop to the other. In your case, there is practically none. If you had radiant baseboard it would be a different story but what you have is convective baseboard that is only transferring heat through radiant heat. You are lucky if you get 10% of the heat that baseboard is designed to put out. Your thermostat won't be satisfied until the room reaches setpoint, and your thermostat can't understand how long it is taking to reach that point (or it would probably pack its stuff and leave. Ha)
Ken
 
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Old 01-22-05, 10:43 PM
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The temperature of the water is too low for a System 2000. Normally these boilers operate around 180-190. The baseboard being 90 out would certainly have some effect but if the old boiler did fine, the new one should too. I've worked on System 2000's for 17+ years & even if I don't like them, properly installed they do a good job. If you can't get any satisfaction from your installer, call Energy Kinetics. They might be able to either build a fire under your dealer or refer you to another dealer.
 
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Old 01-23-05, 12:57 PM
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I don't see a problem with the water temps. The temperature you are setting is the return water temp. And with the drop through a zone usually being up to 20 degrees, you should have 180 going out. What amazes me is the amount of debate about the effect of the improper installation of the fin tube. I have half a notion to put a 10 foot piece in a test environment just to see how little output there will be. Envision this experiment. Cut a piece of cardboard the same size as the radiator on your car and put it in front of the radiator. Run the car liek that for a few hours and see if you notice any difference in the way it works. I think your car would be smoking by the first hour. The only difference is the airflow. It is exactly the same thing with the baseboard. I have had service calls with not enough heat complaints that were related to carpet installations that stuffed the carpet under the baseboard and cut off airflow. So don't ever blame a boiler that reaches high limit for a room that does not get up to temperature. Blame the circulation or the radiation. Go ahead and call Energy Kinetics (800-323-2066) but be sure to tell them about the problem with the baseboard and see what their thoughts are. Ask for Charlie (he is the most experienced tech rep there)

Ken
 
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