indirect DHW with a zone valve vs pump

Hey_Obie

I am working on adding indirect DHW to my oil fired system single zone system. I will have three heating zones and one for indirect DHW. The things I have read seem to favor a pump for the Indirect vs a zone valve.



I bought a nice Wilos ECM pump for my new zone valve system. What are the negatives with adding a zone valve to the indirect?



Thanks

HDE_2

What are the negatives with adding a zone valve to the indirect

Reduced indirect recovery because of possible lower flow potential due to zone valve port, smaller piping, and divided flow if not controlled as priority.

billtwocase

Zone valve

1" Honeywell is what I like. Keeps it simple and reliable. JMHO

russiand

Just did this very same thing

I am not a pro and asked this very question here before. Recently I installed an indirect tank using a zone valve and so far it's working great. I used a Taco EBV 1" zone valve and set it up for priority on my Tacto ZVC-404 control. One pump does it all  for me, and the recovery time seems to be just fine. The only downside that I can see is that you have a single point of failure in the pump. If that goes you loose both the hot water and heat. In my case this method simplified the setup quite a bit. The trick from what I gather is to use a style zone valve that opens fast and has high flow rates.

Hey_Obie

Taco 572 Zone Valve

I was going to go with a Taco 572 1". It has a flow rate of 6-10GPM. I was told I need 6GPM for normal family hot water use ( Not that we are normal).



I just don't know the life expectancy of a zone valve. The circulator that is on my current system has been running for the 23 years that I have been here.



I am going to purchase a backup head for the zone valves just to have on hand if ever needed.

bill_105

THe Taco 500 series valves...

... are real slow to open, like almost a minute. They close real slow too. Amtrol's  new Smartcontrol  actually has a feature to deal with a slow closing valve.

The EBV is fast  but Taco says to use a mixing valve if used on an indirect. I guess if it fails in the open position it's scalding time.

HDE_2

Honeywell

The interesting thing about Honeywell zone valves is the port (inside opening) and ball are the same ones that are used in 1/2, 3/4 & 1". So when you look at the spec's the CV for all valves are the same. While looking at the flow chart, all models start to flatten out at 5GPM. So are the valve sizes just for convenience of pipe size? many would think so.

Unless the indirect is far away and the larger pipe reduces head because of pipe length, fittings, etc, you would be hard pressed to to tell the difference in performance between 3/4" and 1" with H/W zone valves, velocity calcs aside

While I like H/W valves, the White Rodgers for instance outsold them because their 1" and 1-1/4" were as true to full port/full flow as possible.

Big Ed_4

What a Pro would do

We don't like to take chances ...we make our lively hood on our initial install. A call back or complaint costs us money and future business ...



Not enough hot water is a big complaint . Hot water is the largest load on a system ..



The idea is to heat a storage tank as quick as possible . So its better to for us and the home owner to use an independent circulator and full port piping for maximum recovery ... We want to use the full output of the boiler and direct it to the recovery of hot water.



I never heard a complaint about too much hot water Maybe a few of how their daughter is in their shower for 1/2 an hour



Not all are equal with their hot water needs , From Grand Ma to a family of ten is one end of the spectrum to the other ... So some can get away with less ... Sure a zone valve system is cheaper install but an independent and full port piping is better ... Even if the taps on the indirect is 3/4" (Not my first choice )I would run 1" to the unit ... Increase of pressure at the point of heat transfer



So what I am saying the recommendation you hear for an independent circulator is just good practice ..

Nick W

WR 1361 vs. Honeywell ball type

The calculated and measured flow rate of my DHW loop with a 1" WR 1361 valve is 10.8 gpm. With a 1" Honeywell it would be only 6.2 gpm. Calculations were done with Hydronics Design Toolkit.



All three proposals I received for a new boiler called for Honeywells.

Ron Jr._3

What's the pressure drop

through an IFC or weighted or spring flow check ? I'd bet it's pretty close to any size zone valve you would use for an indirect .



I don't see a problem using a zone valve on the water heater as long as you have the option to prioritize in the future ( which is a good option if you use circs too ) .

Hey_Obie

That's an honest answer.

Thanks for your input Ed. I have 1" pipe from the manifold and will be buying an indirect tank with a 1" boiler supply.



I know the circulator pump is the best solution. And it is not a cost issue because both options are about the same. I just felt the zone valve was a little easier on me since I am overwelmed with all this stuff.



Would the Taco 007 with integrated check flow be a good choice?

Big Ed_4

Full Port

Then use a motorized "full port" zone valve , I believe Honeywell makes them ... Give it a shot ... If you find out you need faster recovery durning the winter add a priority relay .



Just make sure you have enough transformer . Transformers are sized by a Volt Amp rating . The constant is 24 volts then multiply by the total amps . Take the amp draw of the chosen zone valve and multiply by how many on the job .… If it comes close to a standard size , buy up one size bigger ... Say you have 4 zone valve with a .5 amp rating 24 V x .5A x 4 = 48VA transformer needed , You can buy a 50VA but it is close ,I would buy a 60VA transformer ... I also like to add a fuse to the low voltage circuit .... A couple of spade connectors and a 3A push in car fuse adds a little safety , mostly from human error ... One direct short and the transformer is toast ...

Jean-David Beyer

I am a homeowner, not a contractor.

For my indirect, there is 1" pipe all the way to and from the indirect hot water heater. The circulator is a Taco 007-IFC. It is a W-M boiler and W-M Ultra Plus 40 indirect water heater. This is the circulator and pipe size recommended by W-M.



They recommend 190F water to the jacket of the indirect, but I do not find that necessary, because my hot water use is very modest. Having it at 190F did not make sense because by the time the water heater thermostat was satisfied, the cold-start boiler had not gotten up to 170F yet.



 My biggest hot water load is my shower that has a 2 gpm shower head in it, and my showers, I guess, last 5 to 10 minutes (I never timed them). I forget how long it took to recover from a shower and a load of dishes in the dishwasher at 190F. I lowered it to 180F, and then it would recover in about 5 minutes. I have since lowered the temperature to 160F, and it recovers in less than 10 minutes.



If I had some teenage girls in the house, I would probably run the supply to the water heater hotter to keep up with them; I am not sure. I want it as low as possible to promote condensing in the boiler.

Hey_Obie

Thank you

All great advice. Thank you.