Check valves on Mixer (tempering) valve

adayton_2

I see on many drawings on the Holby site (http://www.holby.com/). These (27" drop loops) seem to be referenced from the COLD (city) water FEED point to the DHW/Tankless or other HOT Water production device. I may be dense (probably am) but nowhere does it explain the purpose of this loop (in PARTICULAR as related to our checkvalve discussion). If you know of some specific "Holby diagram" that explicitly describes the 27" loop -vs- check valve, please point me there.. Thanks for your patience...

Alfred

adayton_2

Check valves on DHW mixer valves

are called out on the COLD inlet and I believe I have seen them spec'ed on the HOT inlet also. None on the "tempered" output. BUT, when I installed them this way using a tempering valve used as the FEED for a pex radiant heat loop the ball check valve (in the hot feed)chattered incessantly. So I removed them both....and the loop and mixer SEEM to work fine. Should there have been one check valve in the COLD inlet ONLY or in a radiant loop are NONE required?

Alfred/Jim

bob young

CHECK, MATE

IN LIEU OF A CHECK PROVIDE A HEAT SINK LOOP AS PER HOLBY DIAGRAMS.

adayton_2

Check valve/Sink Loop ???

I understand the function of a Heat Sink Loop...It literaly SINKS some of the heat before it can hit the tempering valve, before that in turn hits the pex. while that is important and desirable what does that have to do with check valves? I understand one purpose of check valve in DHW mixer valves is to restrict the COLD water inlet from allowing HOT water to expand back down into the cold water side. I see no harm (perhaps no benefit either) inserting check valve in HOT inlet also (so COLD water can not migrate through HOT side). However DHW is intermittent on/off and I found that with a circulator constantly running a continuous running radiant loop the check valve in the hot inlet CHATTERED incessantly as if the mixing action/activity was causing some kind of high frequency pulse modulation that was effectively rattling the ball in the ball check valve. This is what I was seeking some technical guidance in understanding the reason and performance considerations for using (or NOT using) check valves in a tempering mixer valve in a radiant system that runs continuously.

Alfred

bob young

check mate

you DO NOT understand the function of a 27 " heat sink. check the Holby diagrams and you might get it. the heat sink eliminates the NEED for a check valve. are you starting to understand ?? good luck.

adayton_2

Holby 27\" loop

> you DO NOT understand the function of a 27 "

> heat sink. check the Holby diagrams and you might

> get it. the heat sink eliminates the NEED for a

> check valve. are you starting to understand ??

> good luck.