how do I control the boiler with a 4 way mixing valve and ecm pump

Drewgrizz

I am using a cast iron lochinvar a taco I 4 way and a taco bumblebee out to manifolds and homeruns to myson rads in each room with trv's. My question is how do I control the system? Do I use a simple thermostat in one room to kick the boiler on and off? Also do I need a circ on the primary loop? I heard you don't when using a 4 way mixing valve. I am trying to keep this setup very simple and cheap, is there a better way?

Steve Whitbeck

T stat

I would install a thermostat centrally located. Then you could just use an outside reset control to control the boiler temperature without a mixing valve.

If you use a mixing valve put the pump on the line between the mixing valve and the supply manifold. I take it that the 4 way mixing valve is going to be motor driven to maintain a loop temperature with a boiler return sensor for boiler protection.

Drewgrizz

yes

4 way is for boiler protection and the taco I series comes with an outdoor reset built in. Its 450 or so but takes the place of a pump, outdoor reset, and does boiler protection. So a central thermostat to fire the boiler and let the 4 way and ecm pump do their thing automaticly and the setup should perform.

Steve Whitbeck

Taco

Taco makes an injection control that would be a better choice for doing what you want.

You can install an outdoor sensor to control the mix temperature and it has boiler control and boiler return temp safety. The TACO PC 705 control has the piping diagram.

Drewgrizz

3 pumps

Seems if I use that controller I would need 3 pumps and I dont know if want to run an injection setup. Seems cheaper n easier to just do a 4 way and one pump. I just need to figure out how to control the system?

Steve Whitbeck

Two pumps

With a cast iron boiler and the Taco injection control you only need the system pump and the injection pump. ( cheap Grundfos )

A 4 way mixing valve with the motor drive will cost WAY more than an extra pump.

A 4 way valve without the drive motor won't control boiler temp and it won't do outdoor reset or boiler safety.

If you insist on the 4 way - Taco makes a control for that also that is real nice.

icesailor

Taco "I" Series 4-way:

That Taco "I" Series 4 way does all that with two pumps, nothing else. The valve acts like a hydraulic separator and the primary pump keeps flow through the boiler regardless of the flow through the secondary system pump.

Its really simple but if you try to make it too simple, it won't work. I would use a ECM pump on the system because of all the TRV's but a "Beater Pump" for the primary that will at least equal the maximum flow of the secondary system. If there is no indirect and it is just heating, have both pumps run together. Use the ODY feature for the secondary and let the primary through the boiler run as it may or however you want. 



There are DIP switches on the power head that set the boiler protection for oil or gas. It will set 120 degrees for gas or 140 degrees for oil. It's done with a sensor in the valve. There are two sensors that come with the valve.

If you haven't already installed the valve, and it will be to the RIGHT of the boiler, mark the valve with arrows as to which is the primary and return and the secondary return. The arrows are only on one side and it is easy to have a brain fart if you have been in the habit of riding the short bus to school.

Don't ask how I know.

Drewgrizz

pump

I read that with a 4 way you dont need a pump on the primary side, is that not true? I really like the simpicity of the taco 4 way it seems to have the right features. I have been tryin to understand the boiler controls by reading and it seems like the casties are always on to keep the water in um above condensing, so with the control options of the taco I series 4 way and bumblebee pump and the trv's on the rads I wont need a thermostat, the mixing valve will just dump hotter water into the secondary when the outdoor reset calls for more heat and the bumblebee will keep the water in the lines at a set temp by controling flow rate? I am new to this stuff and am designin my own system so tell me if im off base.

icesailor

4-Ways & Circulators:

Not to be picky, but you should read the installation manual for Taco "I" Series valves.

Clearly on Page 2 of the manual, it shows TWO Circulators. Same as with a 3-way.

Pipe it your way with one circulator and if it doesn't work, its on you. Pipe it the Taco way and if it doesn't work, ask Taco why. Taco and other manufacturers hire people with far more education and experience that I and pay them well. A lot better that I was ever paid. The manual was revised in 2009. If the piping didn't work, they wouldn't be publishing it. Their piping diagrams have always worked for me. Some other way might work for you. I've seen a lot that were piped different and didn't work as well, if at all. But your way might work for you.



http://www.taco-hvac.com/uploads/FileLibrary/102-145.pdf