Open system Zone Valves

Roger_K

I am looking for recommendations for zone valves for an <strong>_open_</strong> hydronic heating system. There are loads of valves for closed loop systems, but open systems seem to be mentioned only as an aside or an afterthought.



I presently have two Honeywell V8043F 1036 valves, which are not suitable for open systems. I need to replace these with something that will allow me to use the same electrical supply and to maintain the same end switch functionality. The present valves have 3/4" sweat fittings.





These valves are combined with a Grundofs circulation pump, all connected to a Polaris PG10-50-130-NV hot water heater, which supplies water for both the domestic needs and the heating zones. The pressure runs about 80 PSI, and the heating zone water temp is about 150F. I can't measure that directly, and the domestic supply from this water heater goes through a mixing valve, so measuring that temp tells me nothing about the heating zone temp.



Supposedly, the Taco Z075C2 valves come in an open system version, but my e-mail to them came back with a recommendation to look at their 571 series. On the Taco web site, the FAQ section points to either a 560 G2 or a 5101 G2 valve. I don't want to buy something only to find out that it is incorrect.



If anyone knows specifically which one(s) from Taco would be a suitable replacement, or any other brand, for that matter, I would appreciate the help very much.

ChasMan

Taco FAQ

I think the FAQ was produced a long time ago pior to the EBV's becoming available. The FAQ appears to be steering you away from brass and towards bronze.

If disolved oxygen is an issue, then bronze or stainless would work better than brass. If they have a bronze version of their new EBV's it should work. The normal ones I have seen are all brass.

The EBV's induce a noise into your pipes when they open and close. I had some early ones that faied. (refused to close intermitently) I replaced them with some second generation ones that failed (again, refused to close intermittently) . I have not tried the new third generation ones although they do appear to be a fairly complete redesign.

If the pump pressure is an issue, then I imagine the EBV's are a no brainer because they are a ball valve which closes tight. Has all the noise of a ball valve too with that satisfying woosh sound as it closes. If Taco has one made out of bronze, it should work. The normal ball is nickel plated brass, Im not sure I would trust that. I have some nickel plated stuff in my PC cooler, It flaked off the aluminum and made a nasty mess and that was in a closed system.

banjodog

ebv noise

I don't know how to quote the previous answer so here I go:



The EBV's induce a noise into your pipes when they open and close. I had some early ones that faied. (refused to close intermitently) I replaced them with some second generation ones that failed (again, refused to close intermittently) . I have not tried the new third generation ones although they do appear to be a fairly complete redesign.



I have a newly-installed system that uses Taco EBV's I believe, and they do make a loud noise when closing. I think I found out why tonight - the pump is running while the valves are closing. It seems to me the pump should shut off a few seconds before the valves close - is that possible?  (Burnham ES2 boiler)  

Empire_2

Water Hammer?

Do you have any idea what your differential shut off pressure is?  This will determine if the valve will close while working against this pressure.  I had a similar problem many years ago and installed a "Watter Hammer arrestor" I think.....  The original noise was most noticeable on closing of the valve.  This was on a loop pump that had a pump always running, so hoping this may help. 

     Is it possible to control the velocity of the water?  Can you regulate the pump,increase line size?



Interesting.  Trying to get a visual on what you have.



Mike T.

banjodog

valve noise

I'm not sure about the pump size, velocity, etc. I'll probably call the installer in the next few weeks to have them take a look. It's only 2 months old.

ChasMan

EBV Noise

The noise I was describing is not water hammer related. These valves are not as likely to hammer as some others since they close very slowly. They make a whining noise. The gear train sounds somewhat like a VCR tape being ejected sans the rattle. That noise is induced into the piping. Again, I am refering to the earlier models. If your valves are hammering, I would imagine any valve you try would hammer.

banjodog

valve noise

The installer came today to look at it and said it is operating normally but would try another kind of valve tomorrow.



My question is this. If the system (Burnham ES2 boiler) starts up in the proper order (call for heat - valves open - pump turns on), then why can't the system shut down in the proper order as well (t-stat happy - pump shuts off - valves close)?  Making the system work that way would absolutely solve the problem!  The noise happens because the pump is running while the valves are closing, and the water has to go somewhere. When the system calls for heat the valves are nearly silent when they open.



But the installer told me Burnham's don't work that way. I find that hard to believe. If the system is smart enough to do it right on a call for heat, it should be smart enough to do it right when it's at the desired temp.

CMadatMe

EP Manifold

If you not against some piping changes, I'd install a Uponor 2 loop plastic ep manifold and put a couple of actuators on it. Still has the same end switch and power function. Gets you away from any problems due to oxygen issues.

Roger_K

Open system zone valves

Thanks to everyone who commented. ChasMan, I think you are right about the age of the documentation. I will look for bronze components.



Chris - probably a lot of work in a somewhat tight space to do what you suggest. It would take care of the dissolved oxygen problem, though, and it is something that i could talk with a knowledgeable hydronic installer about.



Thanks, again. Roger

ChasMan

The issue is..

The reason that it doesn;t work that way is because the Zone valves are a cheap pump controller. Ie, the thermostat controls the zone valve. When the zone valve opens, it makes a little switch (called an end switch) and that tells the pump to come on. Thus, it works in the reverse when the thermostat is happy, it closes the zone valve and makes the pump shut off. If I recall, the EBV valves make the end switch just as they start to open and therefore open the end switch just as they are closed. So, it is the valve that is turning the pump off after it is closed. Not much the installer can do about that.

It is a stupid system. Caleffi valves are a bit better. The end switch makes when the valve is almost open and in reverse, the pump shuts off well before the valve closes. Thats why my system hammers only when more than one zone is on. The Caleffi;s close a little quicker than the EBV's though. Some say the heat motor zone valves are the best when it comes to this. I have never had them so I won;t comment. The Valves should be able to close against a pump without hammering. If they closed a little slower they would not hammer. Ultimately though, I think it is a piping / flow issue. Water velocity is too high. So, you either need bigger pipes to maintain flow or you need to lower the flow speed a bit.