Radiant Set-up questions
Last Post 12 Dec 2014 07:42 AM by sailawayrb. 9 Replies.
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parnorenUser is Offline
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10 Dec 2014 03:46 PM
Hi, I have some concerns regarding the boiler set-up in our house and I am hoping someone here might be able to help. I would like to know if you see anything wrong with the set-up in the attached photo? If the set up is correct, then my question is whether to keep the valve on the "bypass" pipe (between the supply and return line underneath the boiler in the picture) fully open, fully closed or somewhere in between? If I keep it fully open it seems the water travels mostly around in this small loop and not much of the warm water is circulated in the floor loops. If I keep this valve fully closed, then the floor will heat up faster, but when the room reaches the correct temperature, the thermostat closes the automatic valve that lets water out into the floor loop and the pump continues for another three minutes before it turns off. This means the pump is trying to pump water with all valves closed, Doesn't this damage the pump? Sorry If I am being confusing, but I'm trying to understand what was installed in the house. Contacting the plumber who installed the system is not an option.

Attachment: IMG_0831.JPG

Dana1User is Offline
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10 Dec 2014 03:54 PM
I don't see the attachment.


parnorenUser is Offline
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10 Dec 2014 03:56 PM
Finally figured it out. The attachment is now showing.


sailawayrbUser is Offline
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11 Dec 2014 06:16 PM
I would prefer to work from a real schematic (i.e., prefer to actually first design the HR system, create the schematic and then accomplish installation in accordance with the schematic) rather than try to figure out the intended design from someone’s maze of plumbing…sort of like not wanting to use someone else’s tooth brush… So, no comment.

If what you are saying is indeed true that the pump is pumping against closed valves such that it really can’t pump, that’s very hard on the pump…don’t do that...

There appears to be an expansion tank in the far left side of the photo. Diaphragm-type expansion tanks should always be mounted vertically with their inlet connection at the top and should always be installed in the system very close to the inlet side of the circulator pump. Failing to do this may result in air being trapped on the fluid-side of the diaphragm (which can result in premature tank corrosion/failure), may reduce the system's ability to expel air (or even result in air being drawn into the system via the air separators), and may encourage destructive circulator pump cavitation and premature failure.


Borst Engineering & Construction LLC - Competence, Integrity and Professionalism are integral to all that we do!
parnorenUser is Offline
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11 Dec 2014 08:10 PM
It is hard to see in the picture, but the expansion tank is installed Vertically with the inlet connection on top. The pipe below the tank is not part of the system, it just looks that way in the picture. This system was installed when I got the house not long ago and I am trying to figure out if it is a "good" system in the mind of a professional or if it has to be ripped out? I was hoping this forum could decipher the maze that I have by looking at the picture even though it is not a very high resolution photo. (Only allowed to attach a 100kb file) Depending on the answer to my initial question, the pump will work against closed valves if the valve between supply and return has to be closed. At the moment I am keeping it about 10% open to maximize flow through the floor loops and still give the pump a "break" when the thermostat turns off the boiler for the 3min the pump keeps on running. I am still hopeful that someone might be able to give me some guidance.


Blueridgecompany.comUser is Offline
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11 Dec 2014 09:08 PM
System looks good, what I can see anyway.
air eliminator, makeup water pressure control and more. a bit leggy.
System has a yellow bypass ball valve,
Normally we would build with 2 pumps, one primary to serve the boiler flow needs the second to serve the motor zone valves needs.
Your case it is the yellow ball valve acts as a bypass, keep it at about 45 degrees and work your way closer to 90 degrees, the 10% mark might be to much but this is the variable built in by the installer that you will have to figure out. This will protect the pump from dead heading. The intent is to let some water to pass freely through the boiler while letting the zone valves also have the majority.
Expansion tank may be too small, it is the smallest unit out there, check system pressure, you only need about 15 psi.
Dan


Dan <br>BlueRidgeCompany.com
parnorenUser is Offline
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11 Dec 2014 09:41 PM
Thank you Dan! The pressure is spot on 15 psi. Is there a way to determine how much I should have the bypass valve open to optimize the system? When I tried it fully open the boiler cycles on and off much more than when I have it closed or partially open. Is there a spot on the valve where everything comes together in perfect harmony? Would it be prudent for me to install a second pump?


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12 Dec 2014 01:17 AM
The sweet spot in your system related to the bypass valve will be found with trial and error, you are just trying to create enough back pressure to direct thru least resistance the water towards the floor when zone vales are open.
It is an electric boiler, assuming boiler is installed inside the house, all wasted heat will escape in to the building so you're not really wasting heat, just not putting it where you want it, in the floor.
Might check the delivered water temp from boiler, and let us know how the in floor heat is applied.
rule of thumb / though I am sure others here have their own numbers,
staple up 135 degrees , gyp Crete topping pour 90 degrees, surface floor panel system 90 degrees,
These are start points.
Dan


Dan <br>BlueRidgeCompany.com
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12 Dec 2014 01:17 AM
whoops


Dan <br>BlueRidgeCompany.com
sailawayrbUser is Offline
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12 Dec 2014 07:42 AM
Dan has you covered and clearly has better eyes than I do. We always use a primary and secondary pump too. Sometimes the primary pump is built into the heat source.

If your relief valves are not opening when the system heats up (which is when hydronic fluid expands), your expansion tank size is likely okay. The only way to know for sure (or really to properly size in first place) is to run the numbers:

Borst Expansion Tank Design Software

I should also mention that we use a differential pressure bypass valve in our designs (i.e., in lieu of a manual valve) to reduce the potential for hydronic fluid flow noise when only one or two zones are active and to prevent pump dead heading if all the zone circuits were somehow closed at the same time. This eliminates any need to “adjust” a valve. This also increases efficiency by not always bypassing, especially true for mod/con boilers that prefer low return temp.


Borst Engineering & Construction LLC - Competence, Integrity and Professionalism are integral to all that we do!
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