Electronic DHW Tempering Valves

HeatingHelp

This discussion was created from comments split from: Commercial DHW.

BigRob

SWEI said:

Dan Foley said:

This is the first time we have used the ETV. The existing Leonard mixing valve station scales up and is re-built just about every six months due to hard water and scale.

Similar experience here with a couple of large Symmons mixing valves. We recently replaced one of those with a homegrown ETV setup. Film at eleven.

Which brand 3-way ball valve and actuator did you wind up using? L or T ball? Happy with it? I'm thinking about using a Honeywell T775 for the controls.

SWEI

We used an NSF-rated 304SS globe valve.

BigRob

Thanks. Have you seen the Powers Intellistation?

They are using a Siemens actuator. I'm not sure if the 3-way valve is Siemens, too. It does have a plastic "flow linearization" insert.

See page 68 and 69:

http://media.wattswater.com/2915182.pdf

I'm a little confused with what type of flow characteristic they are using.

SWEI

I had not see the Powers -- thanks for the link. At first glance, it looks a bit complex.

Heat-Timer also uses a Siemens actuator. It's fast (20 seconds full travel) but is a rather antiquated design. We ordered a Belimo with a 35-second run time (G21 option, the fastest they offer that family.)

BigRob

I agree. Why all the pressure sensors? I guess I can see sensing for loss of cold pressure but seems like overkill.

I like that powers is using a ball valve. The valve has a characterization and the instructions say it's a linearization insert.

Anybody know what the flow curve is for "normal" full port 3-way valve with an uncharacterized ball?

I'm thing to determine the best mixing approach to ensure high turndown across the ball rotation.

On page 69 of the powers install guide (link above) shows a characterization insert on the intended outlet. What type of response curve is this?

SWEI

BigRob said:

Anybody know what the flow curve is for "normal" full port 3-way valve with an uncharacterized ball?

It's truly awful. Think 100-99-98-97-94-90-80-50-20-10-6-3-2-1-0.

On page 69 of the powers install guide (link above) shows a characterization insert on the intended outlet. What type of response curve is this?

Looks very similar to what Belimo uses. The shapes vary quite a bit depending on the specific flow requirement (seven different versions just for 1/2" valves.) Belimo did not have anything rated for DHW temps and oxygen levels (never mind NSF.)

BigRob

Comparing the Powers pictures to manufacturers, it seems the 3-way valve is also Siemens (makes sense) and the characterization insert is maybe an equal % insert. What's interesting is I don't see a lead free option in this catalog:

https://www.downloads.siemens.com/download-center/Download.aspx?pos=download&fct=getasset&id1=A6V10414605

Also, I think I remember reading the actuator is a super cap close model AND the control unit is made by Tekmar (the product literature states this).

The actuator appears to be the GAP and GNP version:

http://www.buildingtechnologies.siemens.com/bt/global/en/products/hvac-products/damper-actuators/actuators-for-hvac-applications/pages/gnp191_01e.aspx

SWEI

We used temperature sensors and fairly basic logic. Mechanical fail-safes and extra redundancy all sound great, but I'm not currently developing this for market. I have some interesting ideas for demand signaling, but realistically won't have time to pursue development on those for at least a year.

hot_rod

Remember it needs to be low lead and have an ASSE listing to protect you and the customer on domestic water systems. Additional listings possibly in Canada

Mark Eatherton

Let me know if you need access to ASSE Kurt. Their office is in my office in Mokena. They are a wholly owned subsidiary of IAPMO.

ME

BigRob

hot rod said:

Remember it needs to be low lead and have an ASSE listing to protect you and the customer on domestic water systems. Additional listings possibly in Canada

What's interesting is I don't see a lead free version of that Siemens 3-way valve. I wonder if they're able to define the product as the entire assembly, including checks, pipe, unions, etc, then use the total weight in the low lead calculation. Or, they have a special part, which seems very expensive and unlikely, but possible.

If anybody knows what Siemens actuator is being used, please let me know. It looks like one of their bigger "OpenAir" models, but claims to have supercap closing instead of spring return.

hot_rod

Yes it is a weighted calculation for assemblies. It needs to have the low lead certifications to pass inspection.
IAMPO is very proud of their listings, and the $$ show it. It can be certified by others to meet that ANSI standard.