3-way mixing valve for boiler protection

Jeffrey A. Knichel

Does anyone have an opinion on which would be better? Supply or Return mounting of the ESBE valve? I have a 200,000 BTU boiler supplying the old gravity system of the house. The house will have a circutator for the radiators, joining the return to the supply, as the secondary loop. The boiler has a circulator for the primary loop. We will have a pair of closely spaced tees in the secondary loop to circulate the boiler water into the house as the boiler heats up and the Thermic valve lets the supply (or return) water through.

Jeffrey A. Knichel

3-way mixing valve for boiler protection

I have a customer's house with an old gravity hot water system. It has a new boiler and pumped circulation now. I want to use a 3-way motorized mixing valve with a boiler return water sensor to protect the boiler from sustained low temperature operation due to the tremendous amount of water and cast iron radiation up in the house. See pmengineer.com article "Don't Neglect Boiler Protection in Your Next System Design" from January 2003. Figure 3 is exactly how I want to pipe this boiler. My problem is that I cannot find a manufacturer that makes a valve for this application. Can anyone help?

Unknown

Watts makes em

Noel

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Danfoss

Hello Jeffrey:

Danfoss has 3 way valves, and our 92K motor is a set point control w/ sensor included. Would work great in your applicaiton. Please email or call me @ 443-648-1205

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Constantin

There are a couple of providers

Taco makes small (½-1") iSeries 3-way and 4-way valves with integrated outdoor reset controllers. Tekmar and Viessmann also offer larger 4- and 3-way solutions and the external controllers to make them work.

Since this seems to be a high-temp boiler, a 4-way valve may make more sense to prevent flue gas condensation. Injection mixing (via a Taco RMB, for example) could also work. I suppose it all depends on the heating and flow requirements.

Joe Mattiello

You can install a simple by-pass

A simple by-pass after the system circulator, and a flow control valve on the supply to create a pressure drop inducing flow through the by-pass. Measure the temperature at the return where it mixes with the return to balance the system and stay above the minimum safe operating temerature. Alternatively, you can use the Taco, 5000 series mixing valve

Taco, Inc.
Joe Mattiello
Technical Service Technician
joemat@taco-hvac.com
401-942-8000 X 484
www.taco-hvac.com

Joe Mattiello

By-pass loop, or Taco mixing valve.

Try setting up a boiler by-pass loop using a tee, after the system pump, and a flow control valve to create a pressure drop inducing flow through the by-pass to the return back to the boiler. Alternatively, you can use the Taco 5000 series mixing valve. For your reference I attached the submittal data information.

Taco, Inc.
Joe Mattiello
Technical Service Technician
joemat@taco-hvac.com
401-942-8000 X 484
www.taco-hvac.com

hydronicsmike

3-Way Valve - Boiler Protection

Hello.

Have a look at the attached Essay on piping methods.
Pipe as shown in figure 8. We have all three: Mixing Valve, Actuator and 360 Mixing Control to do just what you want.

Please feel free to call tekmar Customer Service at 250-545-7749 and we'll be more than happy to provide a solution for your application.

Best Regards,

Mike

RoosterBoy

Constantin . You On *~/:)

I-series S is a great devise:)

Boilerpro_3

A simple, very effective solution

This is what I do on all the gravity conversion boilers I install and nearly all those with full outdoor reset on the system. The boiler is piped P/S to the system (it has its own pump(s))and the boiler has a Danfoss/Esbe Thermix thermostatic mixing valve on the boiler return (its own pump. No electronics, no motors to wire.....just pipe it in and set the balance valve as necessary.

Boilerpro

Dave_74

Brilliant Solution

The reply by BoilerPro is a great solution to the problem of cold water return to non-condensing boilers.

Use of the ESBE three way thermic valve in a primary-secondary set up solves the problem completely. You can run the system at any temperature, yet insure that water returning to the boiler is 140F. These thermic valves are available preset for 140F. Since they are designed for hydronic systems, the Cv (GPM flow at 1 PSI drop) is fairly high. We use the ESBE a lot in systems, and other brands up to 4" size.

Again, this is a great solution without the cost and complexity of electric or pneumatic valves.

Allied

No circ on primary?

Boilerpro -
I'm new to this; full of questions.
Nice looking installation.
I see the boiler loop with the ESBE valve (and bypass piping/valve) in it set up as a secondary loop.

But here is where I am confused.
There does not seem to be pump on the primary loop and the takeoffs do not seem to use closely spaced tees. Am I missing something?

Also,
it looks like you necked down the piping to the ESBE. What size ESBE do you use (1", 1.25, 1.5")?
Do you have the Danfoss part number for the ESBE valve handy?

Thank you.

Allied

Mixing valve usage.

Joe - interesting idea to be able to use a mixing valve for boiler protection.

I don't see boiler protection mentioned in the submittal data information you provided.
I assume you would pipe the mix/outlet side of the valve to the boiler return, with the cold water inlet being piped to system return.

Question -
The cold water inlet temp for this valve is specd at 38-70F - but system return temps are higher than that. Is this not an issue in using this mixing valve for boiler protection?

Jeffrey A. Knichel

Danfoss ESBE Thermic valve.

Thanks to BoilerPro. That is the solution that I finally hit upon. I called the local Danfoss rep, Wallace & Eannace, and they directed me to their heating expert, Dave McKay. He was driving when I called him, but knew exactly what I wanted to do, and pulled over and looked up the part #. The Danfoss 1 1/4" Thermic valve for the return piping is Model TV465A, Part # 065B8924. The valves come in 1" to 1.5" and have different models for either supply or return mounting. They open at different temperatures. Visit Danfoss North America web site. That is where I found the information.

Jeffrey A. Knichel

I agree with Dave that the Danfoss seems to be a great solution. Simple yet effective. I am a great beleiver in simplicity.

Dave_12

Locate ESBE on return

Jeffrey:

Purchase the 140 F temperature option and locate the valve on the return to the boiler. Specifically, I would install the valve on the return, with a by-pass line from the boiler outlet connected to port 3 on the valve, with the pump between the valve and the boiler return. The valve would act as a mixing valve, with one port (#2) receiving cool water from the system, and port (#3) receiving hot water from the by-pass. The mixed water would exit port (#1) and go back to the boiler at 140 F or above. As the valve senses water temp above 140 F, it will start to close off the by-pass and allow more system water back. It will modulate as required to keep 140 F water as a minimum going back to the boiler.

Allied

TV Thermic Valve

I found the attached Danfoss Sales Brochure

Boilerpro_3

Answers

The 4 pumps on the left upper corner are the primary(system) pumps. The confusion you are having is probably because this panel is a setup that supplies two different water temperatures to 2 pairs of 2 zones, all on full outdoor reset. The closely spaced tees are directly under the black zone pump panel. The boiler loop pump is on the upper right after the air separator and compression tank, water feed connection after the boiler outlet. This does a great job of getting air out. I always use the return mounted mixers so they can respond quicker to sudden changes in return water temp as zones turn on and off. In your case is does not matter as much(single zone), as long as you don't have excessive temperature rise through the boiler. For a typical cast iron boiler at 200,000 input, 160,000 output, a 1 1/4 inch is usually just enough (CV16.4)with a standard Nrf-22, Grundfos Brute boiler circ.

Boilerpro

Boilerpro_3

Answers

The 4 pumps on the left upper corner are the primary(system) pumps. The confusion you are having is probably because this panel is a setup that supplies two different water temperatures to 2 pairs of 2 zones, all on full outdoor reset. The closely spaced tees are directly under the black zone pump panel. The boiler loop pump is on the upper right after the air separator and compression tank, water feed connection after the boiler outlet. This does a great job of getting air out. I always use the return mounted mixers so they can respond quicker to sudden changes in return water temp as zones turn on and off. In your case is does not matter as much(single zone), as long as you don't have excessive temperature rise through the boiler. For a typical cast iron boiler at 200,000 input, 160,000 output, a 1 1/4 inch is usually just enough (CV16.4)with a standard Nrf-22, Grundfos Brute boiler circ.

Boilerpro

Jeffrey A. Knichel

Danfoss Thermic mixing valve

We finally got the Danfoss mixing valve today, and went over and installed it. After playing for a while with the bypass ball valve, we finally got it working where the boiler went up to around 170 degree supply temperature and the Danfoss was letting around 150 degree water back into the boiler. It balanced there and ran for a long time and the boiler didn't go off on limit. It was still running that way when we had to shut it down because the house was getting too hot.
This was exactly what we were looking for. The secondary circulator for the radiation in the house can stay on and is now moving enough volume around to let the radiators all heat up evenly.

Jeffrey A. Knichel

Followed your suggestions

We installed the Danfoss Thermic valve today. See my post below. Thanks for the tips, and we learned another valuable tool for our future hydronic work.