Joined on March 25, 2009
Last Post on March 10, 2014
@ March 10, 2014 8:05 AM in Room heat loss calcsA steam boiler is sized to the EDR of the existing radiation. Have there been any issues with the radiators being able to keep up in certain rooms?
Radiators should be sized to the heat loss. Heat loss of a room is calculated by cataloging all areas that lose heat and, for each area of different construction or facing a different "outside" temperature, calculating Area * (Tin - Tout)/Rval where temperatures are in F and area is in square feet. Then you add it all up and add your infiltration heat loss (this is proportional to the air volume of the room and the air changes/hr value) and that's your total heat loss.
@ February 28, 2014 7:36 AM in Buderus 2107 BLR SENSOR ERRORThey have service literature on the control you're trying to service, which includes the resistance curve for the sensor that would tell you what type of thermistor it is and locate the terminals to which it is wired and trace the leads to the part. If I hadn't been able to find it near the top of google search results I would not have written what I wrote. My default answer is definitely NOT "get a tech" but it seemed like good advice in your case.
So ok, now you have the part and certainly the replacement of the part is comfortably within your skill set. What advice do you need?
@ February 27, 2014 2:33 PM in Buderus 2107 BLR SENSOR ERRORYou have a decently expensive boiler. If you can't search/reconstruct your way to the answer you're seeking, perhaps you should protect your investment by paying for someone qualified to work on it.
@ February 27, 2014 9:20 AM in Logamatic 2107 or Tekmar 260 ?I've had two fried MCBAs, two fried induction blowers, and one fried Alpha on my system (TT PS-60), not to mention sundry other appliances, as a result of overbuilt high voltage lines falling on the domestic voltage lines on two separate occasions. This would be called a temporary overvoltage (TOV) as distinct from a transient voltage surge or line noise; the duration and energy in an event like this is sufficient to blow MOVs in a shunt mode TVSS, and TVSS manufacturers, in fact, do not claim to protect against this kind of event. Since an isolation transformer has 1:1 windings and low impedance, and would simply pass on the higher voltage, it would seem to, alone, be insufficient for handling this type of event. Since the utility can claim an act of god and does not bear the cost of these events, they don't have the appropriate incentive to ensure that these types of highly predictable and destructive overvoltage events are not actively fostered by their engineering practices.
For some reason that is a mystery to me, a panel-mounted TVSS is not allowed to interrupt service in case of a sustained dangerous event that exceeds its protective ability. So you're left with a point-of-use device with fusing that disconnects the line from the outlet in the case of TVSS failure. Of course, not everything can be plugged into a point-of-use device.
@ February 26, 2014 8:11 AM in Ignition failures during warmer, especially humid weatherA watched pot never boils, and I've sat next to the darned thing through many light-offs, all of them worked on the first try. The ground is good, electrode clean and correctly gapped. This can sometimes happen once or twice a day. Never when I'm around, and never ever ever when it's cold and dry outside.
EDIT: As for MCBA 5, there is/was a recall. http://www.heatinghelp.com/files/posts/10281/MCBA_Announcement_8022011.pdf
@ February 25, 2014 11:17 AM in Ignition failures during warmer, especially humid weatherI've got a head-scratcher. Whenever there's a break in cold weather, but especially if it's a very humid day, I get E02 lockouts (five consecutive failures to light off) on the TT PS-60. In cold, dry weather, this is not an issue. Anyone else see anything like this?
For what it's worth, its MCBA type 5 has the known-to-be-suspect ignition transformer, the flat-topped one.
@ February 25, 2014 10:00 AM in The best Delta T for a mod-con?Gosh, good that we have you to bring us all to our senses. ;-)
Yes, delta T changes all the time, but with a lower fixed speed - output held equal - it will be higher than with a higher fixed speed. Which translates to somewhat higher boiler supply and somewhat lower boiler return. Which is what people have been discussing the pros and cons of.
@ February 24, 2014 3:49 PM in The best Delta T for a mod-con?But there may have been insufficient flow for low modulation, causing the boiler to reach setpoint with the water it has in its heat exchanger while there's plenty of much cooler water in the rest of the system. I have seen similar behavior but the boiler was not on high fire. It starts at 50% modulation and it modulates down pretty quickly, but sometimes not quickly enough.
@ February 24, 2014 1:24 PM in Logamatic 2107 or Tekmar 260 ?According to this article, that may not offer all the protection one might desire?
@ February 24, 2014 11:39 AM in The best Delta T for a mod-con?The notion that a lower supply temp, rather than a lower return temp, would lead to more condensing, is one of those.
@ February 24, 2014 11:37 AM in The best Delta T for a mod-con?So, you could expect that, on paper, the boiler would be less thermally efficient. In practice, however, this may not be significant. And with some boilers in some systems, there are very good reasons for boiler flow to be significantly less than system flow (the heat exchanger simply can't flow as much.)
@ February 21, 2014 2:13 PM in Pre-Made Radiant ManifoldsNot all manifolds are made equal, but a decent one will combine some type of on-manifold flow balancing with reasonably accurate flow meters, loop isolation valves, means for bleeding air... On better ones, you can expect that all these features will be somewhat easier to use/more predictable and accurate, and that any replacements that fit the manifold will still be available years down the road when you need them.
@ February 21, 2014 10:53 AM in Not Enough Radiation?I'm not suggesting that it should be in the middle of the room, just that the falling air film from the window might be fighting the convection currents since they're coming right at each other. :-)
The side-discharge that my convectors have seems to create a warm air barrier without mixing excessively with the cold window air. It would be interesting to thermographically compare the two setups, holding all else equal.
@ February 21, 2014 7:52 AM in Not Enough Radiation?Clearly a straight upward shot (and the little bit of added height) would be better for convection if the convector were sitting in the middle of the room, away from any windows or exterior walls that could create downward cold air currents. But it's not sitting in the middle of the room. We're guessing here, anyway - the way to see what's happening would be to place a piece of incense on the outlet and watch what happens with the smoke. Then a cardboard deflector could be temporarily taped in place at a 45 degree angle, angling up and away from the corner between window and back of window sill, and the test could be repeated.
The grill he has appears to be of the "grid" variety, not an expanded metal one. I doubt it's creating any impediment. There's no grill on the intake.
@ February 20, 2014 11:08 AM in Not Enough Radiation?The lower temperature differential means that, with a fixed supply water temperature, the return water temperature increases, meaning that the average temperature of the emitter (and therefore the amount of heat it can emit) increases for any given entering air temperature. In order for this to happen (increased return water temperature WITH increased heat loss from water to air) the circulator has to provide a greater flow of water.
@ February 20, 2014 10:48 AM in Not Enough Radiation?Let me tell you what I did for a particularly difficult room. This room has cathedral ceilings, a small floor area, and three out of four walls are exterior. It had been heated by one five foot and one 3.5 foot convector recessed in the wall like yours (but with the outlet facing the room.) The rest of my house, which I had converted to radiant ceilings (so: a low-temperature system) had been heated in the same way. I used the convector elements that I had ripped out from the other rooms and built triple-pass, counter-flow convectors for this room, then I covered the back of the grill with 1/4" plywood that had cutouts for the computer case fans. I used two 5" fans for the smaller convector and four for the larger. I picked fans of the quiet, low-CFM variety and I'm driving them with 6V even though they're 12V fans. In my case, the desire to use low temperature water was what made the triple-pass approach necessary, and the fans are just there to overcome the greater air pressure drop across the elements and the lower temperature gradient of the air; they're not really "blowing" as much as "circulating." It has worked very well for me. On the other hand, I recall another member not having as much success with his attempt to just increase air movement over a single-pass, low fin count convector.
@ February 20, 2014 9:41 AM in Not Enough Radiation?I can see pros and cons to that layout, but (I think) mostly cons: the convective current could be impeded by falling cold air from the window and whatever warm air makes it out could be getting chilled as it washes the cold glass. A pro would be that I'd expect less window condensation. An outlet facing the room seems like it would have fewer cons.
If increasing the water flow to your emitters doesn't fix your issue, one way to perhaps increase the effectiveness of the convector is to "assist" natural convection mechanically. You wouldn't benefit from very much assistance, looking at that convector (large air passages) but it could put you into the comfort zone with the high supply temps you are using.
@ February 20, 2014 9:26 AM in Not Enough Radiation?Measure the entering/leaving water temperatures at all the convectors, and in the basement at the zone supply and return. This should tell you where heat is actually being dissipated.
You could be hamstringing your convectors by giving them too little flow. What gpm is the Bumblebee saying it's providing to the zone?
If the emitters are simply undersized for this room (was this a converted steam system, for instance?) a supplementary emitter may be required.
@ February 20, 2014 9:13 AM in Not Enough Radiation?Not super-easy to see, but the outlet grill is recessed into the window sill.
@ February 19, 2014 11:26 AM in how prevalent is this?There's a lot more to it than that. None of it intractable or mysterious, but all of it with varying degrees of impact to the final outcome.
@ February 19, 2014 11:16 AM in how prevalent is this?It's good to be skeptical, especially when there is a good reason to suspect that the people who are telling you that "it ain't that simple" have something to sell you. Well, those internet peddlers also have something to sell you, so it certainly pays to be skeptical of their claims. There's no shortage of people who are selling you what they promise is a no-pain, all-gain shortcut to something desirable. If reasonable comfort is what we're after, how do we go about providing it?
It pays to start with understanding the basics and work your way up from there as needed. One size clearly does not fit all, so how do we size a heating system? We do a heat loss calculation for each room. We size the heat emitter in each room to the heat loss of that room, which tells us what amount of flow we require for that room. Is radiant realistic (taking into account heat loss, available area, R-value of any building materials or carpeting or furniture between the tubing and the room, and the installation cost) as the only heat source for this room, do we require a backup source or an alternate approach?
We do our best to use equal length branch piping/loops so that it starts out fairly well balanced and we don't have to resort to balancing valves, artificially creating pressure drop that we will waste energy to overcome. We size the circulator(s) to the total required flow, at the pressure drop of the "longest" branch. We use appropriate materials and fittings (so: no PEX, with its associated high pressure drop fittings, in areas where many fittings are required.) We consider what control strategy would be optimal; some systems may not require a single thermostat (for instance, mine has none) and others may require several. We decide whether we want this system to also handle DHW production, which comes with its own set of design trade-offs. Finally, on the basis of all of this and what economical fuel options are available to us, we pick a suitable heat source and lay out the necessary boiler room piping, paying attention to the ability to purge any air and isolate components that may need servicing so that the whole system doesn't have to be drained. We look at whether there are any possibilities to further optimize our emitter design for the heat source while staying within our design parameters. We balance initial cost against expected operating cost.
We keep track of assumptions/requirements we made along the way and double- and triple-check everything, maybe settle for giving up on some stated objectives if it means that we can save money that we need to save.
Then, once we think we have it all figured out, we hold onto our seat and try to work out construction details, which is its own can of worms!
@ February 19, 2014 10:15 AM in how prevalent is this?I'm simply responding to what I see as "not rising to the occasion" in this particular instance. Saying "nothing to see here," which he certainly seems to do, is usually not the mark of intellectual honesty (again, pertaining to this endeavor and not the man in general.) It's not demystifying radiant heating; it's glossing over details that make the difference between getting your money's worth (whatever the amount) or not.
He does little to address the trade-offs inherent in any design process and to justify why his scaled-back approach will still work. If his mission is to inform and not to misinform, then his approach in this instance would not seem to be a recipe for success. To his credit, he is updating the article but, not having a solid frame of reference, it will be difficult for him to parse out good feedback from bad. (It certainly seems that he was on the receiving end of some bad advice from self-avowed experts so far, and the comment section is largely an unmitigated disaster.)