Honeywell Tempering valve usage questions?

[Vtgent49]

Hi,

Newbee question, but I did search first.

I have 80 gal DHW with solar coil in the bottom, and a side arm hx heated by the boilers primary circulator. On the top exit I have the Honeywell Tempering.mixer. It does get preheated (or prewarmed) water from the boilers DHW coil as the feed to the cold side of the mixer.

The first question is do these mixers make noise when flowing? Somewhere I have noise as DHW is drawn. It seems to be a knocking type rattle, not the tinkling sound of air in the lines.

Second, should I just run the pre-warmed water to the tank, and feed the C side of the mixer with real cold water? Or run a second mixer with real cold? I saw someone mention that they had two. I'm want it to be safe for showers, of course, but I was wondering if the prewarmed water in the cold side of the mixer might be confusing the logic in the mixer, causing the gates to rattle, as they try to cool the outflow.

Thanks in advance.

Al

 

[Nofossil]

I use a pair of Honeywell mixing valves on mine - writeup is here.l Never had any noise at all - works great.

 

[Bob Rohr]

Depending on the model and size most of those Honeywells have a 3 gpm flow rate, at a 1psi drop. You may get some velocity noise trying to flow too much through them.

There are different types of mix valves, with different functions, point of use and point of distribution. Located at the WH would require a valve designed for point of distribution, and be able to accurately track the temperature at the minimum and maximum flow rates you require. Also look for a valve that has the new ASSE 1070 listing and fails to the cold mode.

Depending on how hot the hot feed is, you need some cold water to blend it down to the 120F or whatever you are shooting for. The installation manual typically shows the mix down with various temperature inputs.

hr

 

[Tony H]

I don't know about noise but it looks like the setup Nofossil is using is nearly ideal to give you the right temp water with minimum energy use. Nice design !

 

[88rxn/a]

I use a pair of Honeywell mixing valves on mine - writeup is here.l Never had any noise at all - works great.

ill read this write up later....i bet ittl be good though!!

 

[Vtgent49]

I do have the same AM 1 series, ASSE 1017, 3/4 sweat, right at the 80 gal DHW tank. The noise is getting better, so it's probably just some air that should work it's way along.

I own a spare valve that I could use as a second. The tank hasn't got scary hot yet, 132 is the high. My preheated water is often 128 or so. So, the tempering is adequate for now. I'll repipe something next time I drain the lines for another reason. But I'm leaning towards using one valve and adding pure cold water as needed. The additional preheated water goes into the tank, so it really doesn't seem to be wasted. Plus I like the idea of keeping the tank water fresher by moving more water thru it.

Thanks all!

 

[Nofossil]

In my case, the preheated water could be anything between 80 and 160 degrees, but very often it's in the 90 degree range. That's a lot better than 55, but I don't want to put too much 90 degree water into my DHW tank. The two valve approach gets the absolute maximum usable life out of a tank of DHW. In the 'shoulder seasons', running out of hot water is what determines that I need to build a fire or use the oil. With this scheme, a 40 gallon tank will last three days.

 

[Vtgent49]

Thanks again.

My preheat is boiler DHW coil, which during the cold part of winter could be 130+ all the time. This I can imagine my present set-up, or yours, could use my preheated water for all of the tempered flow. That's why stagnation of the tank concerns me, as it could be the same water in there for weeks? Just letting the preheated water go to the tank is just swapping hot water for hot water (sorta?).

My set-up now just isn't safe, if both are hot, going to one valve.

Hopefully, my solar set-up will take care of the shoulder season. The panels go up next nice day, and the plumbing is done up to the attic. I do have an electric element for final back-up, or I could burn wood or oil as we do anyway in all but a month or two.

 

[Vtgent49]

Update FYI

My storage was 130, and my preheated was 148 (going into the cold side of the Valve). Since the storage was above target, the valve went to full cold, but didn't know the cold was hotter. So the output was 148 to the shower etc. Your basic failure of intended purpose.

I'm going to switch the cold, to well water cold, and stay with 1 valve. Nofossil has this on valve 1, and it gets the DHW water under control, modified later by Valve 2. The very cold water is needed if tempering is the goal.

Thanks all.