Joined on January 11, 2007
Last Post on March 22, 2007
@ March 22, 2007 3:08 PM in balancing one-pipe systems in condo buildingsOh, my! Straight from the proverbial mouth! I've been quoting you right and left to the condo board--including both the article you just referenced and "how to balance a one-pipe system." As I mentioned, the short answers to my question surprised me, as does the fact that our service company has never raised the issue. I've been wondering if I have overstated the need to take a more comprehensive approach to dealing with the heating system and/or over-complicated what actually needs to be done.
@ March 22, 2007 3:00 PM in balancing one-pipe systems in condo buildingsOur building is much smaller, of course, but this (i.e., the Baltimore apt building) is more or less what I expected, in terms of the amount of work involved in balancing the system. I'm confused by the shorter answers.
@ March 22, 2007 2:51 PM in balancing one-pipe systems in condo buildingsI'm surprised by the short answers! Based on Dan Holohan's article (http://www.heatinghelp.com/newsletter.cfm?Id=165), I thought that balancing the system was a multi-step project and that choosing vents was more complicated.
@ March 22, 2007 11:11 AM in balancing one-pipe systems in condo buildingsIím looking for info from pros regarding balancing single-pipe systems in condominiums. Uneven heating/overheated rooms and the need to control heating costs are perennial issues in my small condo (6 identical units, plus garden unit). I believe that the boiler is inspected every fall, but I doubt that the system has been balanced in years, e.g., in the 6 years Iíve been here, no one has ever checked the equipment in my unit. My questions: Should our regular service company have recommended balancing the system at some point or is this something that isnít brought up unless a customer requests it? Is this an indication that our contractor doesnít really understand one-pipe systems? I suspect that the process of balancing the system may raise issues with our bylaws, which stipulate that the components of the system that are within individual units are the property of unit owners. Therefore, the Association does not own and has little-to-no control over vents, radiators, valves, etc. Iíve been told that this is typical of condos. As anyone run into problems related to condo bylaws when servicing the building heating system?
@ February 10, 2007 8:44 PM in Buffer tank questionIn the 5 scenarios you tried, were there any comfort differences or any measurable change in how closely indoor temps were maintained between the different strategies?
@ February 10, 2007 8:32 PM in Mod/con with small zonesMy Prestige was piped so that it can run either direct or P/S. When valved to run direct, I run the internal 15-58 at speed 2. When valved for P/S I run the heating loop on a second 15-58 at speed 2, and the boiler loop at speed 1. It's a real crap shoot to say which way works better. I get the feeling that I get a slightly wider ΔT running P/S at colder temps. It's hard to tell because the North American MCBA controllers count by 2s. I followed the direct vs P/S debate, but I think with monoflo piping all bets are off because you need so much flow on the heating loop that it is hard to widen the ΔT on the heating loop. Is it possible in that case to just widen it on the boiler loop? I don't know... The monoflo mains can almost be looked at as another P/S system. The monoflo mains run much warmer than the branches. Between that and the higher flows, it can't be seen as an ideal way to make these puppies condense their best! The only thing I know for sure is that it costs around $7/mo in electrical costs to run it direct and $10/mo to run it P/S. One switch and 3 valves switches me from direct to P/S. The slowest part switching modes is opening the boiler door to switch speeds on the internal circ.
@ February 10, 2007 6:19 PM in Mod/con with small zonesAs I said in my first sentence, my answer is based on full flow going through the boiler return piping in a P/S layout as is often mentioned as a good way to do it with a modulating boiler. Under those conditions it's the boiler circ that determines how long the coldest water stays in the buffer tank before it gets diluted down temp-wise. It is taking out the coldest water out of the buffer at the GPM of the boiler pump and there are some boiler loops that have high GPMs. ----- How is your buffer tanks piped? It looks like it's a LLH type of setup. It's hard for me to tell from the pic. How much is the buffer tank cooling between firings? If it cooled down significantly, what's stopping the Contender from firing up too high initially? The only clue the boiler has as to what load it is dealing with comes through the change in ΔTs. Is your CH fan speed max capped?
@ February 10, 2007 5:47 PM in Mod/con with small zonesI have a Prestige and also a Prestige bias... No matter which boiler you get it will cycle. You will often only have about a 5K demand. There isn't anything on the market that'll run that kind of load through modulation. In the meantime, the T100i requires a Taco 009 or Grundfos UP26-64 if you want to use the optional flow switch (the Prestige comes standard with one). The Prestige can drive the whole show direct with an internal UP15-58. Only 80 watts on speed 2 to drive the whole show vs 160 to 200 watts just to do the boiler loop for the Trinity. Even less for the Prestige is using P/S because it can use speed 1 (the HX is wide open). The form factor on the Prestige is also better for many installs. Intake and exhaust both off the top, piping all on the bottom. The T100i should be cleaned annually, the jury is still out on whether a Prestige would ever need to be cleaned. It's hard to get much information on the Sentinal controller but it doesn't seem to be as well featured as the MCBA. The MCBA also has the advantage of being a more commonly used by a variety of mfrs. It's made by Honeywell and used by Burnham, Cleaver-Brooks, W-M... they should be easier to obtain years down the line if you need one. The Prestige can't modulate as low but isn't going to need larger / costlier / noisier pumps and will use far less electricity. It also has an excellent control, built in low water protection and a self-cleaning / flow tolerant HX. Still... I agree - it would be nice if they modulated lower. In Europe the same model modulates down to under 20MBTU (5.8KW). No fair...
@ February 10, 2007 3:16 PM in Buffer tank questionRavi's boiler is bang bang with a fixed firing rate. I actually think that your use of a buffer tank may be worse for the boiler than not having it. When it comes on it is having to fire much harder than it needs to because it thinks the system load is larger by th BTUs stored in the tank. So it is worker much harder during its 10 minute firing cycle and then off longer. So what's better? a) Firing at minimum fire for 10 minutes and be off for a short period b) Firing at medium fire for 10 minutes and be off for a much longer period Is running harder to coast longer good? I don't know...
@ February 10, 2007 2:40 PM in High Efficiency Steam Boilers"The cost of such things usually gives no return on investment. But realistically, a similar arguement can be made on condensing boilers in general, at least for the time being." Is this a proven fact or your personal opinion?
@ February 10, 2007 2:09 PM in Buffer tank questionBrad, in terms of using a buffer tank with a modulating boiler with any smarts what you're saying is right but I don't think you are pointing out the best reason for leaving the load offline. When the boiler starts up it is trying to gauge the load. If the whole buffer tank is flowing through the boiler return pipe in the first couple of minutes then the boiler will just think that it has a much higher load than it does. That's the problem. When the boiler first fores it doesn't know the rate of fire it needs. Most of the more sophisticated boiler controls will sense how fast they are heating up the water. The buffer makes the control think that the load is that much higher so it starts off at a higher fire in order to get the water up to target temp. By gauging a front-ended load, the boiler has over-calculated how hard it needs to run. Once the buffer tank is cycled through once, then the boiler has to fire much lower. Essentially these simple full flow buffer tank piping arrangements fake any smarter boiler control into running much harder at the start of a cycle than it needs to. That can't be good, and in fact I'd think it is wasteful and also causes more expansion and contraction stress to the cycling boiler. Using partial flow such that it takes the full firing cycle would be much better because the boiler would do the full cycle at a more consistent firing rate. Best yet is what Brad proposes. Start the modulating boiler off without the artificial load but have a smart buffer control that increasingly blends the return temps down with the buffer water as it starts coming back warmer and warmer. Ideally the control logic should have some idea of how to time it so that the buffer tank finally depletes right at the end of the firing cycle. At the end of the day, buffer tanks are only needed for small loads. Why not try and keep the boiler firing rate at minimum for the full cycle if it can do the job that way? That's a lot of complexity for a home system unfortunately.
@ February 10, 2007 2:05 AM in Mod/con with small zonesIf the buffer is on the return boiler loop getting full flow it may actually be less efficient. The boiler is expecting a steady load. It sets its target fan speed on that - an algorithm based on how long it takes to get the return water to start to warm up. The all important fan modulates up to ignition speed and then full fire or part fire from there. Some go up to full and then modulate down once temps start to rise in the return water or adjusts on the fly and starts based on closer for odr. Either way with a 40 gallon tank and 15 gpms through the boiler loop, that tank's benefit to lower return water temps or add an artificial load are done in less than 3 minutes. It's spent at that point. It also extends the time spent at a higher fire for the boiler to establish the load. In the meantime the boiler isn't going to back down from that artificially higher fan speed until some time after 3 minutes. The boiler doesn't know that load is temporary. A 10įF rise for a 40 gallon tank is 3.2mbtu in far less than an hour - 4 minutes. 15 x 3.2 = 48K. So you just started your boiler off 48K too high saving you from the ravages of short-cycling. How long do these cycles last with the boiler firing that high? NOT AS LONG many times! And every cycle you do this, the boiler is firing hotter than it needs to, wasting fuel and doing larger expansion/contractions per cycle. When that boiler tank's 40 gallons are spent, if the boiler is firing 48K too high for the sustained load and it has a small capacity HX, what happens to the water temps. Way past target, easily out of condensing range... small volume system with 48K of oversizing! If you are going to use a buffer tank, I really feel that the effect of the cooler water has to last about the length of a full cycle. You want the cooler water from the buffer tank near the end of the cycle. What might be best to do is have a smart controller and a very small ultra low watt VS injection pump in a separate indirect loop off of the boiler return. At the start of firing cycle it does nothing. As return temps start warming up, it mixes them down. It targets the flow to the expected duration of the firing cycle (a TRV could also work). Still, the tanks take up a lot of space for something that controls can totally take care of. If you add a buffer tank, try and maybe measure consumption per DD before and after. You can actually see if there's a change. I'm going to put one in, but it'll be fixed partial flow. Maybe when in years if I get a VS pump I'll control that flow more. At partial flow it stands a chance on helping a bit.
@ February 9, 2007 2:09 PM in Vari-vents and cost control in single pipe steam heat systemThank you for the suggestion. I don't know what a heat timer is, but I'm sure that a quick search of this site will answer the question!
@ February 9, 2007 2:05 PM in Vari-vents and cost control in single pipe steam heat systemI appreciate the prompt reply. I can't begin to tell you how much bad advice we've received regarding the heating system. Re Vari-vents--this isn't the first time that I've heard that there are better options. I'll pass this info on to the board. A major problem with our setup is that the radiators, valves, and vents are considered private property--owned by each condo owner. There is no consistent, system-wide strategy regarding vents. I'm still not clear about where the savings factors into this, given that the thermostat in one unit controls the overall heat cycle. Does correct venting result in a longer period of time between the cut-out pressure and the cut-in pressure? Thank you for your advice.
@ February 9, 2007 1:08 PM in something awryIs your outdoor sensor exposed to and able to read the true outdoor temps?
@ February 9, 2007 12:37 PM in Mod/con with small zonesJim, it's pretty well impossible for a single boiler to modulate to all ranges. At some point, they fall below the minimum modulation and that's where the controls kick in. My experience is limited to MCBA controllers (a common control used by many manufacturers). It has numerous settings that will allow you to very strictly control, how it fires. For instance: ∑ You can set it so that when it fires, it fires for 10 minutes at a time - it then varies the time interval between firings and you won't sense that this is even going on. ∑ You can set a minimum time between firing cyles for up to 5 minutes. ∑ You can cap the fan speed for heating only so that when it does start up it never exceeds what you need for design day, like a governor - this is especially good on multi-zoned systems to limit the HP the boiler might think it needs as various zones keep coming on. If it's allowed to go to high fire when sensing the colder loads coming back as zone open up, it won't be able to run as long before it hits the ODR target return temp. ∑ You can also use the differential/hysterisis settings to tune how it cycles. Until, boilers can modulate more than 10:1, understanding how the controls can be used to tune the cycling characteristics of these machines will be paramount. You also have to remember that cycling off isn't a bad thing either. If it is only firing half the time in milder conditions you won't sense any comfort differences and you'll be saving on your electrical.
@ February 9, 2007 12:19 PM in Vari-vents and cost control in single pipe steam heat systemPlease help me understand how installing Vari-vents on radiators in over-heated rooms (as recommended by the condo board) will save on heating costs. Here's the situation: 80+ year old condo building with 6 units/3 floors, plus garden unit. A thermostat in one of the first floor controls the boiler in the basement. How does installing Vari-vents on radiators in overheated rooms in other units result in energy saving? (My guess, given the location of the thermostat, is that this is related to the boiler cutting in and out in response to the pressuretrol, i.e., the burner won't be on for as long with Vari-vents. Is this close?) Is this likely to be cost-effective? (Less important technical question: I understand that traditional vents close when steam reaches the vent. What triggers a Vari-vent--or any type of vent that traps air in a radiator--to close?) Thank you
@ February 9, 2007 12:12 PM in Gorton S/A Vents Availability In Canada?Have you tried Noble? For that matter, why not call Gorton or email them and ask? http://www.gorton-valves.com/
@ February 8, 2007 10:10 PM in How to figure volume in gallons re hydronic systems.Doesn't Rhomar have a chemical that you add to the system and then the amount it dilutes gives a close number of the volume?
@ February 8, 2007 2:53 AM in Baby it't cold outsideI heard that Greenland actually has a surplus of women. I also heard that it's ice colored and the Iceland is green - go figure.
@ February 7, 2007 11:59 PM in washing machineexactly the same thing here - it jumps like mad and can;t balance - the rest of it's okay but its a dancer still have my 14yo old maytag dryer - works perfect still should have had the old washer fixed in hindsight - the tranny wouldn't do the spin cycle - a fair amount of corrosion on the outside, from life beside an uninsulated concret block wall half above ground didn't realize that performa was a different company that maytag had recently purchased - this was top of that line and the price seemed right and the name was good i'm thinking that the square looking maytags that are fairly simple looking and very conventional but not cheaper are the ones to get direct drive on any of this equipment makes of disposability - i can't imagine any front loaders lasting 20 years but hopefully i'm wrong