Excellent Info on hydronic mixing systems

[DaveBP]

For those of you not familiar with the Caleffi Idronics online articles or not in the habit of checking them out regularly the latest is a very thorough and detailed explanation of various different schemes for using mixing valves in hydronic systems. Great illustrations (a picture being worth at least 900 words) and even a few systems using solid fuel boilers and heat storage tanks.

They have a European slant on things, which can be very innovative by American standards, and do 'suggest' their own products in the process.

If you always wanted to buy Siegenthaler's books but didn't want to spend the money, their series of articles are nearly as detailed without as much algebra. And they are free.

http://www.caleffi.us/caleffi/en_US/Site/Technical_library/Idraulica_magazine/index.sdo

(As always, you may need to copy/paste this URL into your browser to get it to work).

 

[kabbott]

I have just skimmed through the article but looks like a good read for diy'ers.... page 6 should be a must read if you are not using return temp protection

I am looking for info on mixing valves for return protection on my new boiler, I was just killing the secondary pumps when the boiler return temps dropped on my
old system. I would like to use a motorized mixing valve that can be controlled by a 4-20 mA signal from my Nofossil control system along with variable speed primary pump
to control inlet and outlet temps.

Any opinions on brand/reliability/price?
Taco i series looks like a good price but not sure I can control it with the NFCS.

 

[leaddog]

I have just skimmed through the article but looks like a good read for diy'ers.... page 6 should be a must read if you are not using return temp protection

I am looking for info on mixing valves for return protection on my new boiler, I was just killing the secondary pumps when the boiler return temps dropped on my
old system. I would like to use a motorized mixing valve that can be controlled by a 4-20 mA signal from my Nofossil control system along with variable speed primary pump
to control inlet and outlet temps.

Any opinions on brand/reliability/price?
Taco i series looks like a good price but not sure I can control it with the NFCS.

Watch ebay for motorized valves. I bought honeywell 1 1/2 valves and motors for less than $100. It takes alot of searching and research to find things that will work but with so many factories leaving that high end stuff is out there. I just saw a siemens 1 1/4 valve and motor go for $20 yesterday. Some are controlled with 0 to 10v and some with 4-20ma so just make sure they match. Lots of controllers and pid's out there also.
leaddog

 

[kabbott]

Thanks for the tip leaddog. Lots of valves on ebay now but little in the actuator department.
esbe makes one that takes a 0-10V/4-20mA signal, not sure who else does. Looks like Tekmar only makes 24v floating actuator... not sure of a good way
to control that with my NFCS.

The price on new ones is a little tough to take.LOL I will keep looking on ebay. If I have to pay the price for a new valve/actuator I will just use two pumps like the Econoburn
setup and run them variable speed with the nimbus control. Money saved will probably pay the electric difference for the next ten years.

Kris

 

[in hot water]

The variable speed solar controllers on the market will run any brand, off the shelf, circ up to a 2 amp current draw. Maybe NoFo can "embed" the same relay into his control. It's a tiny relay, about the size of a postage stamp! Omiron G3MC 202P-VD.

Then you have the ability to use a pump with variable speed for return protection and for you heating pump.

hr

 

[Nofossil]

The variable speed solar controllers on the market will run any brand, off the shelf, circ up to a 2 amp current draw. Maybe NoFo can "embed" the same relay into his control. It's a tiny relay, about the size of a postage stamp! Omiron G3MC 202P-VD.

Then you have the ability to use a pump with variable speed for return protection and for you heating pump.

hr

I have a variable speed drive that I'm using that works with most circulators. It has a couple of nice features like a momentary full power 'bump' to get the circulator spinning if you're starting the circ at a low speed. It also cuts off below 30% power, since most circs will stall somewhere around 20-25%. I'll look into the Omron, but I'm very happy with the one I have.

 

[kabbott]

That Omron number just looks like a solid state relay.... soon to be discontinued at that?

NoFo, any "easy" way to "accurately" control one of the 24v floating valve actuators with the NFCS? Looks like a common with a terminal for CW and one for CCW rotation.
How do these work, does the control constantly cause the valve to hunt back and forth to control the temp. I mean there is no way to know the position of the valve correct???

I assume the proportional (0-10v/4-20) actuators a signal of say 5v or 12 mA would put the valve 50% open.

 

[Nofossil]

That Omron number just looks like a solid state relay.... soon to be discontinued at that?

NoFo, any "easy" way to "accurately" control one of the 24v floating valve actuators with the NFCS? Looks like a common with a terminal for CW and one for CCW rotation.
How do these work, does the control constantly cause the valve to hunt back and forth to control the temp. I mean there is no way to know the position of the valve correct???

I assume the proportional (0-10v/4-20) actuators a signal of say 5v or 12 mA would put the valve 50% open.

Yeah - I looked at the Omron part. It's being discontinued. It and the replacements are just relays as far as I can tell.

Some of motorized valves that I've seen have no position feedback. I guess you could 'jog' them once every so often , then wait to see if you need to jog them again in one direction or the other. They move pretty slow, so you could also drive them to one end, then drive them back for some measured interval that corresponds to the position that you want.

In the NFCS, the 4-20ma output is software scaled to a 0-100 range so that a software output of 0 provides 4ma and a software output of 100 provides 20ma. This is complicated somewhat with the Nimbus drives since they're a 4-20ma device that shuts off the load at 8ma. You'll have a chance to find out soon enough ;-)

 

[leaddog]

Thanks for the tip leaddog. Lots of valves on ebay now but little in the actuator department.
esbe makes one that takes a 0-10V/4-20mA signal, not sure who else does. Looks like Tekmar only makes 24v floating actuator... not sure of a good way
to control that with my NFCS.

The price on new ones is a little tough to take.LOL I will keep looking on ebay. If I have to pay the price for a new valve/actuator I will just use two pumps like the Econoburn
setup and run them variable speed with the nimbus control. Money saved will probably pay the electric difference for the next ten years.

Kris

The valves I'm refering to are industial 2or 3 or 4 way valves and are controled with PID's usually 0-10v or 4-20ma. Honeywell, siemans, MAC, johnson and others. The valves are sometimes interchangable with motors but you have to research that. Sometimes you can find a valve and motor together but with a smaller valve and then find a valve to fit and still come out cheap. The honeywell setup I have cost over $2500 retail but I have less than $100 in it. I'm pretty sure the NFCS probaly would control these also but not sure. The pid's are neat to watch as they will auto-tune and open and close the valve to the set degree.
leaddog