Joined on January 18, 2012
Last Post on September 25, 2013
@ September 25, 2013 9:04 PM in ac system design helpI'm doing an air system design course hopefully this winter.
Since I wrote the original post, I have acquired a ductulator and learned some useful formulas, which has opened my eyes quite a bit.
Regarding the Trane AC manual - is it available directly from Trane? I don't see it on their website.
@ September 25, 2013 9:02 PM in ac system design helpLooks like it's going to be mini-splits after all. Owner doesn't want to compromise celing height. Thanks!
@ September 17, 2013 5:01 AM in ac system design helphey guys,
I have a potential customer who wants zoned AC in a small office space using a multi-split heat pump. Did a load calculation & found that each office requires 5-600 BTUh of cooling, obviously mini splits are a bad idea (smallest indoor unit I can find cools to 9000 BTUh.). So I am looking at other ideas.
The entire office suite is only 1250 sq ft and could in theory be cooled by one mini split if it were open concept, but each office/room requires its own zone.
I've been thinking about presenting the customer with other options, such as zoned ducted AC with a variable-speed air handler and motorized zone-valve style dampers. However, I'm not up on AC duct sizing. Don't want to undersize.
Is there a sizing rule-of-thumb for AC ducts, something I can do to get a basic calculation of sizing for the purposes of working up an estimate?
I am doing a duct design course this winter but this job came up too early!
Thanks guys! If anyone has other ideas on how to configure this system, I'd love to hear these also
@ February 28, 2013 4:51 PM in re-piping an old rad system...She will get the respect she deserves.
Gutted, yes, but restored to her former glory. The GC on this job is some sort of "heritage home" specialist. First time working for him but apparently this is what he does. I looked at 2 other jobs with him today, similar heating situation. Won the bid on this one BTW, and looks like there might be more in the future.
Thanks everyone for your help. I love the Wall.
@ February 28, 2013 9:42 AM in re-piping an old rad system...natural gas maybe in about 20 years. Electric baseboard heat is king here. A large portion of my work is converting systems from oil-fired to electric boilers.
@ February 28, 2013 9:41 AM in re-piping an old rad system...It seems to me, in theory at least, that with a home-run loop from a radiant manifold to each radiator, it could be possible to zone room-by-room with an actuator snapped onto the head of each balancing valve. Once the flow is properly balanced to each rad, install the actuator and set up the controls.Or, at least pre-wire it for future room-by-room zoning as an upsell.
I'm aware of course that a TRV would do the same job a lot easier fom an installation perspective. Just thinking "out loud".
Ivanator, your idea sounds exactly like what I am trying to accomplish. You asked why zone room-by-room. It has a lot to do with culture and construction around where I live
We are experiencing the 10th year of a housing boom/suburban sprawl in which every new home is a turn-key job with electric baseboard heat. Hot water heating is perceived, sadly, as either something from a bygone era (older Victorian homes like these, with poorly-operating heating systems) or very expensive/only suitable for large custom homes (in-floor jobs).
In cases like this job, where a major renovation is taking place, I'm bidding against an electrical contractor who wants to put in electric heat. To win the job I have to offer the same features of electric heat, the most common of which is room-by-room zoning. I'm quoting for people in their 40's who grew up with oil-fired hot water heat, single zone, badly-running system, and is swayed to electric for that reason. I have to give them all the features of electric. A common sentiment is expressed "I like those big old cast iron rads, but oil heat (sic) is always so uneven, the thermostat is downstairs and upstairs gets too hot etc etc"
@ February 26, 2013 8:19 PM in re-piping an old rad system......everyone for your replies.
I've looked through a few threads on this topic (there are a few here) and it seems like a few have used radiant manifolds to successfully zone radiators. I'm pretty sure I'm going with this idea, using one manifold per zone. More than likely going to zone with circulators, so one circulator per manifold. As for the sizing of the home-run circuits off each rad, I'll be doing a heat loss calc soon...waiting on the owner to decide what type of insulation & windows he will be putting in.
Steamhead, to answer your question TRVs are an excellent idea, but not for this particular system. The original installer tried to do a monoflo system using regular tees, and thus very out of balance. Subsequent homeowners have put up with it because "those rooms are cold, that's the way the heat is". This house will be strip-to-the-studs renovated, so I am re-piping it entirely.
Chris- I like your suggestion but not familiar with systems using a 4-way mixing valve. How would one arrange the near-boiler piping on this type of system.
Eric - Love the drop-ear idea. Will be using it. Neatness definetly counts.
@ February 26, 2013 10:51 AM in favorite zone valve?I'm partial to the Honeywell zv myself...readily available, easy to swap out when needed, seems to last a good long time. I've worked on systems with honeywell ZVs that must have been 40 years old, still working fine.
I wouldn't mind trying the Taco sentry one of these days though. I like most of Taco's stuff, just haven't given their zone valve a try yet.
@ February 26, 2013 10:40 AM in help with measuring airflowa vane anemometer would be better for this particular situation?
I use the magnehelic for balancing procedures, and the anemometer for measuring at terminals such as diffusers, grilles etc. I don't use the pitot tube very much
@ February 25, 2013 8:09 PM in re-piping an old rad system.....the way I see it, with a premade manifold for each zone (I prefer Uponor myself)and a zone circ for each manifold.
Have you used this set-up before? Do you find that 1/2" tubing provides adequate flow to each rad.
@ February 25, 2013 4:31 PM in re-piping an old rad system...I'm looking at a re-pipe job involving an old Victorian-era home heated with cast-iron rads. The system is currently all one zone. I'm re-zoning so that the system has either:
-one zone per room
-one zone per floor (3-5 rads per zone)
I'd like the zoning to be a bit more user-friendly.
Has anyone re-piped a system this way before? I'm looking at a one-zone-per-rad scenario using 1/2" wirsbo HePex to/from each rad, controlled by either a zone valve or a dedicated small circulator.
I wonder, though, will such small zones cause short-cycling of the boiler? It is a non-condensing, cast iron oil fired boiler with domestic immersion coil.
If short cycling could be an issue, I will instead pipe it with one zone per floor (that's 3-5 rads per zone).
In this case I'll pipe reverse/return, or maybe get my hands on some monoflo tees. Not really common around here
My main question is, will the one-zone-per rad setup work, or will there be problems?? Haven't done it before with old cast-iron radiators. Panels yes, cast rads no.
@ January 15, 2013 9:27 PM in Glycol in a Snow-Melt Systemthat looks kind of like the chart I used to have. To answer your question, it is a de-icing system for the bays, not a "true" snowmelt. It is worth noting though, that the bays are open on one side and do not have doors of any kind.
Our coldest recorded winter temp was -9 F, our average cold temp is 11 F.
@ January 15, 2013 6:12 PM in Glycol in a Snow-Melt SystemI am doing up an estimate to replace the propylene glycol in a snow-melt system at a self-serve car wash. Went there today on a service call and found that the glycol solution had been freezing. What is the typical glycol-to-water concentration for a snowmelt system? I haven't done one before. I've done the typical 50/50 solution in home heating systems...should a snow-melt system have a stronger concentration?? I used to have a chart for this but can't find it now.
@ November 15, 2012 2:12 PM in Recent Jobswell thought-out pipework. Gotta love those Taco zone controls too, I use 'em on every boiler job. Really simplifies and tidys up the control wiring.
@ November 15, 2012 2:04 PM in Follow up to "possible blocked radiator" situationSome of you might remember my thread regarding a "possible blocked radiator" which seems to actually be a direct-return system with a balancing problem>
Well today I began the process of trying to remedy the problem. First thing I tried was, thinking that maybe I made a boo-boo during the roughing in stage, cross the supply and return lines at point A in the attached diagram. Re-filled the system, purged air, and started it up again, and within minutes the whole zone, including the problem radiator, was heating. With the supply and return to the sub-zone crossed, every rad in the zone received heat. So far, so good.
I then took readings with the infared laser thermometer to see how out-of balance everything was. The two top left rads were the hottest at 130 degrees, the problem one was around 105.
I think with valves installed to throttle flow to the two top left rads, I can send some more heat to the sub-zone and hopefully even things out.
@ November 14, 2012 5:27 PM in series-loop design questionand I agree with you.
I told him first that the issues were usually found on potable systems and at fittings; explaining that his was a heating system with very few fittings, and that I didn't see any corrosion. I first offered to pressure test his system and document the results to put his mind and the inspectors mind at ease. However, there is no stronger force than public opinion, however wrong it may be...he's had some potential buyers walk away because of the Kitec, and home inspectors armed with only half the information aren't helping, so he wants to remove it to get the ball rolling.
Too bad about Kitec though, the idea behind it was right on. I'm interested in the Pex-Al-Pex with stainless compression fittings that Ipex makes for pneumatic air piping. Looking forward to using it on my next commercial job.
@ November 13, 2012 10:27 AM in series-loop design questionJust came by to measure up existing pipe & heater lengths.. Homeowner is sending me all the info I need room dimensions, window sizes etc. They have expressed that they are sufficiently warmed without costing too much though, so my guess is that what I come up with will be close to what the original installers came up with.
Mostly what I'm worried about is friction loss from pex fittings. Not really set up for Uponor, it'll most likely be a crimp job. The only fittings are at the boiler and at each heater.
@ November 12, 2012 5:25 PM in series-loop design questionThe series loop is the simplest piping design but after (during?) a major problem with direct-return piping (see my other thread "possible blocked radiator") I'm second guessing everything I do.
I'm pricing a re-pipe job that involves a 15-year old 5/8"Kitec series-loop system. Guy is selling the house, home inspector wants the Kitec removed. I'm going to price re-piping it in 3/4" heating pex with crimped fittings. I want the system to perform as good as it ever did before re-piping. It's 4 zones, zone valves pumped with a Grundfos UP15-58 (equivalent to a Taco 007).
I'm going to keep this job simple. Run the zones in series-loop just like it already is, substituting 3/4" heating Pex for the existing 5/8" Kitec. Sounds simple enough.
My question is: Will the friction caused by the pex crimp fittings (insert) be "too much", leading to a need to upsize the circulator? Should I recalculate the head, adding an extra pick-up factor to allow for the internal crimp fittings that I will be using with the heating Pex?
@ November 11, 2012 3:11 PM in possible blocked radiator?-Installing some valves in the lines feeding/returning the left side of the zone, allowing only the sub-zone to operate. If I can get all 3 rads in the sub-zone to heat sufficiently, I'll slowly open the valves to the left side of the zone, hoping to achieve a balanced flow. I may use globe valves to allow for throttling flow.
-I might also consider a larger circulator. Although the 007 on high speed will generate enough head (10ft), it has no head to spare. Some flow noise might be acceptable as there is virtually none now.
-If I have to, I might consider making the sub-zone it's own zone with dedicated zone valve. I'm trying to see if I can get it working without doing this though, because running the thermostat wire will invovve a small amount of tear-up.
@ November 10, 2012 12:27 PM in possible blocked radiator?Icesailor, let me see if I understand you so far.
In the revised version of the diagram attached, the area inside the black square symbolizes exposed piping in the basement (everything else is behind finished walls).
I could install ball valves to shut off flow to the rads on the left side of the house, leaving only the sub-zone open. If I'm understanding you correctly then the sub-zone will work, because if doesn't have to share pressure with the low-resistance left side. The longer runs on the sub-zone offer higher resistance and are now getting less flow.
If this ball-valve experiment works, it would be safe to assume that, if the sub-zone became its own zone, all three rads in that line would work. Right or wrong?
Another thought: Instead of ball valves, install balancing valves (or globe valves) at the points indicated by white circles in the diagram?
And one more: The system is now running at the usual pressure, 12 psi. I generally don't ever set residential systems any higher than that. Would a pressure increase help things, do you think?
Anyway thanks everyone for your help thus far.
@ November 10, 2012 11:28 AM in possible blocked radiator?Sorry Icesailor, if I said monoflow it was accidental. Meant to say direct return, NOT monoflow or series-loop