Flow problems

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Old 08-26-06, 11:45 AM
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Flow problems

I have a 5 zone closed loop system and I'm having problems with one of the zones. It's a new system and all the zones have isolation values installed, which I'm so glad I had done during the installation.

I isolate the zone by turning off ball valves at the start and end of the zones and I then connect a hose at the start of the zone to the drain valve, then I open the drain valve at the end of the zone. When I do this I only get a small flow of water. I also have a pressure gauge setup so that I can tell if I have air in the system. If I close one of the drain values, the pressure gauge slowly comes up to the 40 PSI of my water system. When I open the valve, water escapes and the pressure falls to 0, the flow is very small.

I can do this same procedure with other zones and it works as expected, lots of water, lots of pressure.

However, the problem zone is the biggest zone I have and I'm wondering if that's the problem. Its 58' of 3/4" baseboard, 133' of 3/4" copper, 86 90's, and 23 45's. The system operates at 20 PSI. This is all one continuous zone.

The master plumber who installed the system says that he has had residential loops longer than this without any problems and he says he sent the specs to the supply company's design team for them to review. They all don't see a problem with it.

The problem I have is with logic. If my water system that operates at 40 PSI canít push water through the pipe then I donít see how the circulating pump can do it.

Any help, suggestions, or comments will be appreciated.

Thanks,

Jerry
 
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Old 08-26-06, 05:20 PM
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Flow problem

It sounds like you are not feeding water for one reason or another. Some pics would help. With 191 feet of pipe/baseboard, 86 ells, & 23 45's, I'm I would be amazed if you could flow water thru that zone with a typical residential circulator. Beyond that I'm at a loss but Xiphias has a great deal of experience with a zone flow problem. Hopefully he will see this thread & jump in.
 
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Old 08-26-06, 06:52 PM
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Resident one-trick pony here!

Do you have circulators on each zone, or zone valves and one circulator pump?

What pump brand/model?

This big zone has a total equivalent length of about 425 ft. (I added 10 ft for risers). That's a huge loop. Most residential zoned systems shoot for about 250 ft TEL. I have a loop that goes around 325 ft TEL, and that is considered quite long. Head in your long loop at 4 gpm is about 13.24 ft. You'd need a large residential to light commercial pump such as a Taco 0010 to move water through that. A 0010 gets you about 3.7 gpm, which is a decent flow rate for that zone. A Grundfos (I think 15-58) multi-speed would do about 4 gpm on "medium." A Taco 007 would be at shut-off head (i.e., no flow).

86 90s and 23 45s? Wow. You live in a corkscrew-shaped house?

A concern here would be if this is a valved system, when this zone isn't running, the huge pump would be working on the other zones. If they are smallish, then you will probably experience velocity noise. High velocities can also lead to pipe erosion. Anything over ~6.5 gpm is not good.

If this really is a head/resistance problem, one possible solution is to put this zone on a dedicated circulator. A Taco 008 would be a decent choice.

More info on your system would help.
 
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Old 08-27-06, 05:09 PM
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More information

Thank you very much for your replies.

There's pictures at:
http://webpages.charter.net/taylorjl/IM001783.JPG
http://webpages.charter.net/taylorjl/IM001784.JPG

As you can see it's a valved system, 5 zones and two pumps.

In IM001783.JPG, you'll see the five zones. The three on the left are in floor heat zones. The two on the right are baseboard zones. I have everthing labeled but you'll probably have to download the picture and zoom in to read them.

Both pumps are the same model. They are Grundfos UP 15-42F. The specs are as follows:
3 speed:
speed 1: 10 GPM, 12' head
speed 2: 15 GPM, 15' head
speed 3: 17.5 GPM, 17' head

I don't know the length of the second zone but I don't get any velocity noise. It's probably about the same length as the first zone except it doesn't snake through the old part of the house so there's a lot less 90's. It's going through new construction.

The boiler is a Lochinvar Solutions CBL180.

The house isn't a corkscrew but the piping sure is...

Also, I know I'm having an air problem with that zone. I'm fighting with trying to get all the air out, I can't imagine why with all the 90's... I've also got a couple leaks, as you can see by the picture of the expansion tank. That has been fixed, I hope.

Thanks again for your help.
 

Last edited by taylorjl; 08-27-06 at 05:13 PM. Reason: forgot something
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Old 08-27-06, 05:52 PM
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Yowza.

Grady and/or Furd will have to weigh in on the details of the piping.

Comments:

1) Major thing that immediately leaps out as a problem is that pump1 is pumping toward the expansion tank, rather than away from it. Huge no-no. I speak from experience, having lived with a similar set-up that had major air problems for most of last winter. Once we fixed that, the system has run silently ever since. Search around here for "repeated air problem" and you will find a four-month tale of woe. Skip to the end for links to sites and books that explain the importance of "pumping away" from the expansion tank (aka the point of no pressure change, aka PONPC). You could remedy this by swapping the positions of pump1 and the air eliminator/expansion tank. Particularly on long loops, the negative pressure induced by the pump is so great you are below atmospheric. Assuming you can pump through this loop, moving the expansion tank connection to the suction side of the pump will fix the air problem. Repeat: this is EXACTLY the problem I suffered with last winter.

2) What kind of in-floor system is this? I've never seen 3/4" copper for radiant applications (I'm not terribly familiar with radiant, but generally speaking it's low temp, low velocity, which typically is not a 3/4" copper application. What is the design temperature of these loops? All the same? All different? Lengths?

3) The right-most radiant zone has a bypass just after the zone valve. Where does it go? The Shelby box is blocking the view.
 
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Old 08-28-06, 04:28 AM
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Answers:

1. Pumping away from the expansion tank seems logical. I'll make that change.

2. The in-floor heat is 1/2 " PEX tubing in concrete. Each loop is about 150', there are 12 loops through the whole house. 11 in concrete, 1 small loop under a joist floor. The guy I hired to do this didn't know much about in-floor heat. He knew more than I did (i think) but I knew enough to keep the loops at around 150' and to use Oxygen Barrier PEX. The design temp is all the same but I don't know exactly what the temp is. That's another thing I have to do, install a temp gauge on the low temp loops.

3. That's not a bypass, it goes to the first five in floor loops. I'll post another picture.

http://webpages.charter.net/taylorjl/IM001785.JPG

I'm not too happy with this guy's work to begin with and now...
 
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Old 08-28-06, 03:31 PM
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Flow problem

OMG, what a mess!!! Sorry, but it's no wonder you have problems. I guess people just don't understand manifolds.

Xiphias is 100% right about the pumping away thing & I must admiit that I learned a lot from his ordeal.

Most zone valves create a lot of restriction. For example a Honeywell V8043F-1036 is rated at 3.5 gpm & a V8043E-1021 is rated for 8.0 gpm. Both are 3/4" sweat valves.
If you can provide model numbers, I can find out more about your particular valves.
 
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Old 08-28-06, 04:06 PM
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Scared...

Ok, no one likes to hear "OMG, what a mess...", now I'm scared.

The zone valves are V8043F-1093.

I just finished reading the famous xiphias "repeated air problem" thread. Yes, I read the entire thread. Very interesting and I will apply the lessons learned from that ordeal.

Thank you, thank you!! for sharing this information and your knowledge. This is a great forum.
 
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Old 08-28-06, 04:55 PM
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Good News

Ah yes, the famous, or infamous as the case may be, repeated air problem. Boy, did I ever have to eat crow on that one.

Now for the good news: At least the valves you have are high capacity valves (8.0 gpm).
 
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Old 08-28-06, 05:19 PM
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Ok, that IS good news. And hey, I read the whole thread and it doesn't appear to me that you had to eat crow. You're trying to diagnose a hot water heat system without even seeing the system, I mean come on... even experts on site didn't catch it. We have also learned a great deal from that post, especially those of us who know nothing...

Anyway, back to my problem. There was an OMG in your previous post that I'm still stuck on. If you have enough time; Knit-pick please. I'd appreciate your comments and I now have a strong desire to learn everything I can about fixing this mess.
 
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Old 08-28-06, 07:34 PM
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I have little to no experience with mixed systems. For that matter, little experience, period. I have become sort of a hydronic wannabe and in the course of learning about things have done a lot of reading, researching, etc.

So my free opinions.

First, know that I have come to terms with how poorly installed my system is and am slowly squirrelling away the funds needed to rectify it. Fortunately (?), it is taking quite a bit of time to find a decent local installer so there's no rush. I'm a very competent and hardcore DIYer, but I don't have the time or resources to get tooled up for gas combustion appliances and the related electrical, piping, etc. I'm hiring a pro and it will be worth it. Point being if you want nit-pick, I'm happy to give it a shot. Book-smart, anyway. Pardon any coarseness.

The piping layout is pretty bad. That's probably the biggest issue. It's inefficient, looks hard to maintain/service, nothing looks labeled, wires are left hanging rather than organized and well-routed, etc. Grady is spot-on about the manifold thing. There is a very simple and efficient way to pipe hydronic systems that just seems lost on many people. FWIW, your high-temp return "manifold" looks a lot like mine.... In practice, maybe once you fix the pumping away issue and ensure that you meet the head requirements of your longest loop, everything will be ok. But, there are MUCH MUCH cleaner ways to pipe this. I've got some pics of nice systems found on the web. PM me with your email and I can shoot you some if you want.

This system should probably have been piped as a real primary/secondary system with a variable speed injection pump serving the radiant zones. This allows you to have the high temp baseboard zones served off the primary loop, and the injection pump supplying only that water needed to get the radiant zones up to temperature. There are a bunch of ways to do this, including a new generation of mixing blocks such as Taco's RMB-1 and tekmar's Mixing Station 704. Or an installer could build a primary/secondary loop system from scratch.

Your set up is, technically, I guess, a primary/secondary system with the mixing valve serving as the separator between a primary loop and the radiant zones. Three-way mixing, however, is kind of a low-rent way to do this. There's a nice explanation of mixing schemes for radiant at the tekmar website. Go here

http://www.tekmarcontrols.com/literature.html

and check out the essays section, esp. the one on mixing methods.

It also looks like you lack control of the system. You could control both the radiant and the high temp zones with an outdoor reset controller that would match the supply water temperature to your building's heat loss as determined by the outdoor temperature. More comfort and less fuel. I think Grady's not a huge fan of these kinds of controls, but in your multi-temperature system, I think it makes sense.

Lastly, check the specs on your air elimination device. Some of them require a straight length of ~16" of pipe on the inlet side. But first things first, get to pumping away and see what happens.

Another thing that leaps to mind is yes, the radiant loops are short, but what is the delta-T of the loops? Radiant usually is designed for about a 10F delta-T (return temp is ~10F lower than the supply temp. This provides good heat transfer. Given how you're running a lot of short loops off one zone valve, I don't know how this might affect things. Presumably your installer and/or the supply house design people figured all this up properly.
 

Last edited by xiphias; 08-28-06 at 07:50 PM.
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Old 08-29-06, 03:53 AM
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Thanks for your opinions, they are appreciated. I guess my goal is to get to your level of book smart. I'm looking forward to seeing those pictures of good practice plumbing... I'll also read all the links I find on this forum. Thanks again for the time and energy you guys put into this.

There's a source that I was thinking of using when I started this project. http://www.radiantec.com. This site has a bunch of pdf docs geard for the DIY'er.

I know the wiring on my project is bad. I'm redoing that this weekend along with now moving the tank, adding some temp. guages and some overall clean up. I'm kind of a neat freak and this is driving me nuts.

Thanks again.
 
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Old 08-29-06, 04:47 PM
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Taylorjl Re: OMG

Xiphias knew what the OMG was all about & pretty well summed it up. No need for me to say it all over again. Thanks, Xiphias.
 
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Old 08-29-06, 05:39 PM
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Great, thanks.

I got some reading to do.

xiphias, you mentioned power purging, or reverse purging in one of your other posts. How exactly did he do that?

Grady, you mentioned that people just don't understand manifolds. Do you have any examples or documentation that describes best practice design for manifolds or will I get to it if I start reading the already provided links?

I have a several changes I can make right away. Move the pump in relationship to the expansion tank. While doing this I'm going to look into the spirotherm vent. I'm going to shorten my longest loop, the problem loop, by removing 16' of baseboard and associated piping. Doing this will reduce my largest loop by about 75' TEL, reducing head, etc.

I'm going to expand my shortest in-floor loop to cover what is lost by removing 16' of baseboard, which is my kitchen and dinning area making the pergo toasty. This will balance out my system a lot. It will also provide radiant floor heat in my ceramic tile entry. Something I should have done to begin with.

I'm going to install some temp gauges, another isolation valve, or two depending on how much pipe I have to move for the spirovent and tank/pump move. I'm also going to clean up the wiring and label.

Thoughts/Opinions
 
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Old 08-29-06, 06:39 PM
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Just make sure you do your heat load/supply calcs properly. There is not a 1:1 relationship between radiant and baseboard. You can't get as many btu's out of radiant as you can with baseboard. So -16 ft of baseboard (~8800 BTU/hr) might need a lot of radiant floor to make up the difference. I forget what an average radiant floor can do, water temp and output-wise. It's not a lot.

Also make sure the flow rates and delta-T's work.

In all, sounds like more work than it's worth, if the original problem can be solved by one or more of moving the expansion tank connection and perhaps putting the problem zone on it's own circ to satisfy the head requirement.

good luck!
 
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Old 08-30-06, 05:32 AM
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power purge

My power purge consists of taking the indirect water heater drain, connecting a hose to it, then attaching it to the drain valve where the return enters the boiler. In my system, that creates a flow of water through the boiler, the loops ,and all the way back to the boiler. It also does it at domestic pressure with warm water. I'm not completely sold on the "warm water has less oxygen than cold so there's less to eliminate when you heat the cold water" argument. Yes it's technically true, but if your system is piped right, it should get rid of the air regardless. In my case, the indirect is the closest available source of domestic pressure in a hose.

Your system is valved/drained such that you get basically the same effect the way you're doing it now. Blast through the drain on the supply side, drain out the drain on the return. With all that other piping, it's possible there's some air elsewhere and it all ends up in the most sluggish, problem loop, but given how it's piped, you're probably doing the best you can do.
 
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Old 08-30-06, 04:28 PM
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Thanks xiphias, you've been great with all my questions. Youíve all been great.

Warning... mild rant.

A note to all those out there who are looking for a contractor; Ask questions! I was asking a lot of questions of my installer and it appeared to me that he was getting frustrated with me questioning everything. Now, as someone who deals with questions on a daily basis, I'm used to it (getting asked questions) but not everyone is and I understand that. However, if you are paying someone to do something for you, you are the customer and you are always right or at least you have the right to ask questions. If they (your installer, contractor or designer) doesn't like it then find someone else. I know, easier said than done because I've been there a bunch of times. I knew better with this installer and against my better judgment, kept him on the project.

I hired this guy because he was suppose to be a professional and know what he was doing. The fact is that he was a bull in a china shop type guy who had the 'geterdone' attitude with what appears very little pride in his work. Then there's the type of person who is too much of a perfectionist to the point that nothing gets done. Find someone who is a happy medium, ask for references (and check them) and ask to see some of his work (and actually go see it). Oh and ask more questions.

If you buy a house and it's this way it's a little easier to take then hiring someone to install a mess. It just adds a little more insult to injury.

end of rant.

Thanks to all for reading and replying to my questions.
 
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Old 11-10-06, 10:21 AM
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Update

It's been a few months since my last post and here's the rest of the story...

Back in August, I replaced the pump and expansion tank location. This was going to be my first attempt to get water flowing through my largest loop. I basically reconfigured the system by placing a spirovent where the pump was and hanging the expansion tank from the spirovent and also bringing the water supply into the bottom of the spirovent. This all worked very well. I was able to get the air out without any problems. Very cool, except I still had a flow problem.

I could pin point where the problem was and where the heat stopped by feeling the pipe. After the pipe left the boiler, at the 6th 90, I could hear significant water noise. Shortly after that 90 the pipes and baseboards would take a long time to warm up.

I went through a bunch of things in my head. Could it be blocked? If so, how and by what, an acorn, stone or something...? This was my longest loop but could air or pump size still be the issue? I re-did all my calculations, my pump was big enough to handle the size of the loop. I could open the bleeder on the baseboard after the 90 and get good water flow. I was stumped.

I drained the system again and put an air fitting on the baseboard bleeder after the 90. I then cut the pipe in a convenient location, but as close to the 90 as I could, hoping that I could blow whatever might be blocking the 90 back or at least hear something rattling. No luck. I then took a piano wire and fed it up the pipe to see if I could feel anything. That didn't work because the 90 in question was the 4th in line and I couldn't get to it. I had a hard time getting the wire past the first 90 not alone the next two.

I put everything back together just incase I knocked something loose and tried it again. Still no luck.

So, I re-did my heat calculations and determined that I could easily shorten this loop and replace the baseboard in my dining room with in-floor heat. So I did just that, shortened the loop by about 75' TEL. This is the corkscrew portion of my house where the old part meets the new and doing this would reduce several 90's and potential air traps, which is what I thought was happening.

After reducing the size of the loop, filling the system and purging the air, the system works perfectly. All zones heat up quickly, good flow, no noise and some significant satisfaction.

After this job I had a bunch to do at work and just threw all the copper pipe and fittings into my "junk" shed and would finish cleaning up later. Well, the other day I was cleaning and discovered something very interesting. The 90 where I was having the problem was about 90% blocked because of a malformed 90! Just inside the flange is what looks like a blob of copper. The pipe that is sweat into the fitting doesn't go all the way in, but far enough that it wasn't noticed during install.

So, my flow problem was caused by a blockage and I probably didn't have to shorten this loop. I'm much happier with the way it is now though and I learned a lot.

Thanks to all for your help, especially xiphias. The reference materials and opinions where very helpful.
 
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Old 11-10-06, 12:57 PM
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Excellent. Thanks for the update. Glad we could help.
 
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