Joined on September 16, 2002
Last Post on August 21, 2014
@ August 21, 2014 12:32 PM in legends of the south poleSupercooled water in clouds is a pilot's worst nightmare. The stuff is liquid -- rain, for all practical purposes -- until your wing and tail hit it. Then it turns into ice, heavy ice, practically instantly and you de-icing gear can't get rid of it. If you're really lucky and have been living right, you fly out of it into warmer air and can recover. If not you have an unplanned encounter with mother Earth, which can ruin your whole day.
@ August 19, 2014 8:15 PM in EDR and margin of errora pretty substantial margin for wiggle room in figuring EDR for a system. As NBC said, the best approach is to look for a boiler which is reasonably closely matched to what you figure your EDR to be. Within 10 percent for your EDR calculations is just fine.
@ August 16, 2014 10:04 PM in Temperature-based cut-in for a Vaporstat?I do hope that your time delay is set long enough so that the system does coast up to a high enough temperature to turn off the thermostat.
If not, and the timer times out and the thermostat is still calling for heat, you are going to take quite a hit on the efficiency because you will need to bring that teakettle back up to a boil...
@ August 16, 2014 10:02 PM in Temperature-based cut-in for a Vaporstat?I watched this thread with some interest... I'll be very interested to know if there is a significant fuel savings given identical building conditions (that is, the same amount of overshoot if any at the end of your setback cycles). Frankly, I have my doubts about whether you will be able to tell, as the signal will, I think, be buried in noise.
I did want to respond to a comment in one of the early posts in the thread on "short cycling".
That's a bad term, and I do dearly wish that we could get rid of it.
There are three completely different things involved here.
First, the "short cycling" to which you refer towards the end of a heating cycle. A far better term would be "pressure modulation". What is happening is that the radiation cannot condense the steam quite as fast (one hopes -- if the boiler is reasonably closely matched!) as the boiler can produce it. Since you don't want the pressure to rise, it is necessary to modulate the rate at which the boiler produces steam to match the rate at which the radiation condenses it. One could use a burner where the firing rate varies with pressure, in exactly the same sort of way that the power of your car's engine is varied with load to maintain a constant speed on the hifhway. There are no burner systems that I know of which do this on oil or gas, although there are multi-stage burners which can come closer. So, lacking that capability, we turn the burner on and off to maintain the pressure within a narrow range. In many systems, the minimum off time is set by the burner post purge and pre purge cycle; the on time will be what is required to bring the pressure back up. Is there a loss of efficiency here? I'm not really sure. The burner is off only a very short time, and thus the system never really comes off a boil, never mind cools below boiling. If there is a loss, it is minor -- perhaps half a percentage point, overall.
The second type of short cycling occurs when system shuts down on pressure before the radiation is filled. This almost always indicates that the main venting is inadequate, although it could also indicate that the steam main size is too small (that would be unlikely in an older system). This does have efficiency implications, as well as comfort implications -- the ends of the system get poor heat.
The third type is, in a way, a combination of the first two, and occurs when the boiler is badly oversized.
The second and third types to affect efficiency and fuel usage, no question.
One might add that an ideal system would modulate the firing rate so that the boiler would never shut off, but would fire only just hard enough to match the heat loss from the structure. This can be done with a vacuum vapour system, if you can pull enough vacuum (the heat output of the radiation being, then, a function of the vacuum level and thus condensing temperature) and, of course, can be done rather easily with an hydronic system by varying the water temperature going to the radiation (or the flow).
Back to square one -- I know of no burners with that wide a modulation rate....
@ August 16, 2014 9:21 PM in Yet another boiler sizing question from a newbie...it really is six of one and half a dozen of the other. Either way, they need to be right. Traps have some real points (one reason why they are so common!) in that they either work or they don't, and if they are working properly then you have no problems with getting the right steam flow into the radiators. Orifices, on the other hand, have no moving parts to fail, so if the pressure is right, they will always work -- once they are properly sized for the radiator.
Take your pick...
Traps, I might add, can last a very very long time if they aren't abused -- all the traps on my system are original (about 85 years old). A couple of them have failed open, which would be a nuisance except that I also have Hoffman valves, and the solution is to set the valve to meter the flow, just like an orifice would. Which works just fine. I could replace the failed traps but, honestly, I'm too lazy and too cheap!
You will want a 0 to 16 ounce vapourstat. Set it initially to cutout at 12 ounces and back in at 6. You can dial it down some if you find it works better that way. A low pressure gauge (it can be on the same pigtail) is a big help to make sure that the 'stat is working the way it should; sometimes they do need a bit of calibration. One other type: a snubber (look at http://www.omega.com/pptst/PS_SNUBBERS.html for examples -- must be steam rated) will help to stabilise the vapourstat and prevent it from turning off prematurely on brief blurps and surges.
Keep the standard pressurestat (wire them in series) as a safety backup.
@ August 14, 2014 3:07 PM in radiator steam traps vertical pattern single unionIn fact, there are a lot of systems which were built with orifices. There are a lot more systems which were built -- as nicholas noted -- using valves for the same purpose (the one in the place I take care of is in that category).
Traps on such a system are somewhat in the belt and braces category -- they serve to control things in two situations: first, someone monkeys with the valve and gets it open too far and, second, somehow the pressure gets too high.
I'm reaching a bit out on a limb here, but it is my feeling that you won't be any worse off if you reduce the pressure first, and I'd be very much inclined to bring it right down to about 12 ounces cutoff with a vapourstat. If your church just doesn't have the cash to do that, try taking the existing pressuretrol as low as you can get it to work reliably, which will probably be around a pound and a half cutoff.
This won't hurt anything at all.
Then start with one zone, and put orifices on the convectors which have failed traps first.
Then do the next zone, and so on.
Then go back and work on the ones you didn't do the first time around.
Believe me, I sympathise with the budget woes of churches...
@ August 14, 2014 2:56 PM in UPS or Surge Protection - Condensing Boilersurge protection and power conditioning are two very different things (a UPS is a form of power conditioning).
Surge protection protects against just one thing: overvoltage spikes on one of the hot wires with relation to the neutral. These spikes can be lethal to equipment; depending on the particular bit of hardware, the shape and size of the spike may or may not be a problem (a big old old electric motor, lots of copper, lots of iron) may not be affected by something which will completely fry a bit of digital electronic equipment. If spikes are the problem, the surge protection may be the answer. I would point out that there are flavours of surge protection.
Power conditioning, on the other hand, takes whatever power is coming in and hopefully manipulates it to produce -- in the best forms -- a smooth sine wave or (in three phase) sine waves with the correct nominal voltage between phases (if three phase) and the neutral. It's not that hard or expensive to do for relatively small loads. It begins to get very expensive indeed for larger loads.
One needs to define exactly what the problem is that you are dealing with before figuring out what equipment is necessary to achieve the desired result.
@ August 13, 2014 7:45 PM in Oil fired flue without barometric damper?with icesailor here (and I have sailed over most of that area, too!).
I don't see how, I really don't, you can have anything like a reasonably constant draught on that boiler without two things, neither of which I see: a barometric damper, to reduce the variations in draught from variations in the wind, and a control damper. You might get away without the control damper...
The key thing to remember here is that a burner can only be properly adjusted for one draught condition (assuming, of course, that it isn't self-adjusting!). Some seem to be more tolerant of variations in draught than others, but it can only be correct at one draught. Now if your draught in the chimney is varying, and there is no control for it... at least some of the time that burner is operating out of adjustment, and maybe way out of adjustment.
@ August 13, 2014 7:35 PM in Geothermal vertical loopsYour lake water heat exchangers are 10 to 12 feet down, so in the winter time they are in water which is about 39 F -- 4 C. In order to heat your facility, you need to extract the heat from the water in your loop going through the heat exchangers and raise it's quality (that's the job of the compressor). That's going to cool the water coming from the lake -- the heat has to come from somewhere, after all; there's no free lunch. So the return water to the lake is going to cooler than 39 F. Problem: you only have, at most, a 7 F temperature difference to play with (actually, you'd want to not use all of that -- say 3 F temperature difference, max.
Now the the heat which you can extract is a function of the temperature difference and the flow rate, just exactly like hydronic heating -- same formula. And, like hydronic heating, to get more heat you either need more flow or more delta T. You don't have the option of more delta T, so you need more flow.
I haven't seen your installation -- obviously -- nor have I seen the design documents, nor the controls. From the sound of things, however -- based on what you have written -- it sounds as though you need three things: more flow in the lake loop -- probably a lot more flow -- and, most likely, bigger heat exchangers in the lake; you are working with a very small delta T on those heat exchangers, so you are going to need to move a lot of water. You also need a control logic which cycles the compressors off when the temperature of the return water to the lake drops to some low value -- I'd pick somewhere around 35 F or 2 C as the minimum. That way you won't get the freezeups you mention.
@ August 13, 2014 3:53 PM in engineerthat small radiator at the end of the main to which you refer may be important for getting proper venting of that main. There has to be a way for the air to get out of the steam main -- either into the dry return to which you refer, or into the air.
@ August 13, 2014 3:50 PM in radiator steam traps vertical pattern single unionJoe, I love it.
You are right, though -- sizing the orifices is a bit of a hit or miss proposition, although there are sizing guides which can get you close.
In answer to the pressure question, you can make an orifice controlled system work on almost any pressure, believe it or not -- but it is much much easier to make it work on a very low pressure, such as you can achieve with a vapourstat set to cutout somewhere around 12 ounces or so, and cut back in around 6. That should be all the pressure you would ever need for this system.
@ August 13, 2014 3:44 PM in Geothermal vertical loopsLake Huron -- and Georgian Bay -- does sometimes freeze over. But it does not freeze to the bottom. As has been pointed out, at some depth -- and probably not that far down -- you will have lake water at a more or less constant 39 F (4 C). From this a properly designed geothermal system should be able to extract all the heat it needs to heat your property or, conversely, reject all the heat you need to manage to cool your property.
There are two approaches: a closed system, in which you have a system of pipes in the lake (probably at or very near the bottom) with sufficient surface area to extract or reject the heat needed, or an open system, in which you simply pump lake water through your geothermal system heat exchangers directly. Unless you are in a particularly grungy area of Georgian Bay, I would think the latter would work just fine.
So the question is -- why was the system unsuccessful? What, exactly, were the lake conditions which caused problems?
I have not drilled wells in the granite in that specific area (if it is granite?) but in general wells in igneous or metamorphic rock has rather poor yields, and may be quite unsuited for open system (pump the water out of one well and back into another) geothermal.
@ August 11, 2014 8:27 PM in One riser or two?they should both be 3 inch. As has been noted, two 2 inch are actually smaller in area than one 3 inch.
There is some advantage to having two, but on the 75 it isn't really necessary, provided that the rest of the header piping and all is correct. I'd put my effort into building a drop header for it, instead of going with two 3 inch -- you'll have better steam quality.
@ August 8, 2014 10:04 AM in Replace gravity with pump in condensate line?Gravity works every time. No power outages. No failed pumps. It just works.
There is no reason at all why a condensate line has to have a consistent pitch. It can very happily go down under something, and around a few corners, and then back up to the boiler. Granted, it would be advisable to put a cleanout plug at the lowest point, but you don't have to have a continuous pitch.
@ August 6, 2014 9:52 AM in Condensate Return Line Cleanout System: looking for recommendationsis a good idea -- although you may find that once a year is more than enough. Surprising how clean steam is...
If it were mine to play with, though, I'd have a ball valve where the lines meet the boiler piping, so you could isolate the boiler from the returns (not a bad idea anyway -- that way, with a king valve on the connection from the header to the house system you can completely isolate the boiler if you even need to raise the pressure on it slightly). But I wouldn't bother with big valves on the rest of the return system -- they're expensive. Instead, have drain cocks (you need them anyway) and use T's with a threaded plug. Just close the main valve, open the drain cocks, undo the plugs and blast away with your hose...
@ July 31, 2014 9:44 PM in Drop Header???I suggested that welded steel just might be the way to go. In places where you need to be able to disconnect piping, or need to allow a little give in the assembly -- like hooking up to the existing steam mains -- I'd use flanges welded onto the pipes.
@ July 31, 2014 9:42 PM in Oil to Gas Conversionand, as vaporvac notes, you are not planning to add radiation in the future, the IN5 is the one to go with. One of the things you want to avoid with steam is getting the boiler oversized. It doesn't help any in getting more heat, and will cost you money not only in the boiler itself, but it won't run as efficiently.
Match your boiler to your radiation.
@ July 31, 2014 4:30 PM in Drop Header???used both tappings on the boiler... give him credit for that, perhaps.
A drop header will give you much dryer steam. It may also be a little easier to pipe in, all things considered. Yes, I would use 5 inch for the connection from the drop header to the existing system, and I would use 5 inch for the header itself. The risers and the pipes coming over and back down to the header can be whatever size Weil McClain recommends for that boiler (yes, I could look it up, but...). You would connect the two risers to the header, near each other -- say 10 inches apart to 20 , then 10 to 20 inches further along connect a line going and over to the system connection (you might put a king valve in that; there is something to be said for being able to shut off the system and confine the steam to the boiler and near boiler piping from time to time -- but 5 inch valves were not cheap, last I looked). Then, finally, make your connection down as the equalizer.
Do it in threaded black iron, or welded steel, please. Not copper!
@ July 27, 2014 2:05 PM in Builing an additionforced air is not more efficient than hot water. In fact, a properly installed and controlled hot water system is the most efficient way to heat your home. Furthermore, it's a lot more comfortable than forced air.
So -- I would recommend that you replace the old boiler with one properly sized to fit your home, including the new radiation (consider baseboards or even radiant floors in parts of the new second floor), with proper controls (including outdoor reset) and zoning.
For cooling you probably should replace the old central air; you could use another unit, or mini-splits, in the new upstairs.
@ July 26, 2014 9:18 PM in Another Steam Boiler Sizing ConcernI thought they were a little better than that. Charles tells me that Cedric, my nice Carlin fired oil burning Weil-McClain, manages about 85 after he's finished playing with it, so I figured a gas unit would do as well...
@ July 26, 2014 7:28 PM in Another Steam Boiler Sizing Concerngas boiler, whether powered or not, should be able to achieve 85% efficiency. So that is not a consideration.
What is far more important is that the boiler be sized to match the radiation, which your contractors appear to have done. An oversized boiler will be nothing but trouble. Don't do it.
@ July 25, 2014 3:35 PM in handling power outages on a wellas usual...
A few other comments, though.
The main one is that your available volume in a power failure will be the effective volume in the pressure tank -- that is to say the air volume between the high and low switch pressures. In your storage tank, that would be exactly zero since you have no air in there! That is if you are depending on air pressure. However, you could have an elevated vented tank, and depend on gravity instead. If you did that you would have the total volume of the tank available. Can you place the tank in your attic? That would give you enough pressure for most fixtures. You would need to isolate the tank under normal conditions as the attic placement would only give you about 10 psi.