Thermostatic Temp Control of Water Recirculation

BigRob

Does anyone know of US available parts like this temperature controlled valve for water recirculation?  I have a 4 branch DHW recirculation system that was never setup with balancing valves.  I'd like to find an automatic setup the control the branch temperatures.  Are there any good US solutions?  It seems like this type of setup hasn't made it's way from Europe yet. 



Check this out:



<a href="http://heating.danfoss.com/PCMPDF/VDD3I102_MTCV%28LLC%29.pdf">http://heating.danfoss.com/PCMPDF/VDD3I102_MTCV%28LLC%29.pdf</a>

Mark Eatherton

Contact Bob (Hot Rod) Rohr with Caleffi...

He showed me one that is American that is exactly what you describe.



You can also drop a variable speed constant pressure pump on it and save even MORE electricity, gas and wear and tear. Just make certain that the pump body is compatible with the highly oxygenated water you will be dealing with.



ME

BigRob

Thanks

Thanks for the tips. Our current recirculation system is essentially a building heater right now - around 5 therms/day. It seems to be over pumped and the temperature drop seems pretty low. The unbalanced branches are also causing trouble when I try to turn the pumps down. In that case it seems like water is flowing in the wrong direction sometimes. There are no check valves on the branches.



I will now turn on the Hot Rod signal light.

SWEI

Overpumped

is unfortunately the norm here in the US.  I've got commercial jobs running on ecocirc Varios that nobody believed would get the job done.  Using several small pumps (one per zone/line/wing/etc.) can save a lot of time adjusting things.

BigRob

Not a bad idea..

Do they make a stainless vario?

SWEI

No stainless

but they're brass, and NSF.  Mostly used for recirc, though I find them fantastic for small hydronic loops.  Slight PITA adding unions to both sides, but the adjustability and miniscule power consumption are hard to beat.  The version with the built-in check valve and union has a lower curve.  Wish they made them with EU-style threaded union ends.  Even better, give me one with a 0-10V input.

BigRob

Cool pumps

I do like them. I was just reading about demand based recirculation setups for mult-family systems. I think that approach might be best, even economically. Those danfose thermostatic valves are absurdly expensive when I look at European prices and they only reduce the overheating of the continuously circulating loop. I've only seen a couple off the shelf demand systems and they are a simple control scheme- very easy to use a cheap PLC controller, flow sensor, and temp sensors for the same functionality. The SW is simple, too, just some AND logic. I'm thinking a small pump sized accordingly to each branch with a temperature sensor for each branch. The question is: at 4am how long in time and how much flow would I need to have reasonable heat up. Unfortunately, there doesn't appear to be an opportunity to install flow sensors at the supply of each branch- maybe one sensor for each half, although there are no as-builts. Have you seen a demand system in action?

SWEI

Demand-based recirculation

Can work quite well.



Here's an easy way:  Install a relay with a 120V coil (or a current switch) on the hot lead between the bathroom or kitchen light switch and the fixture (you can direct-wire the pump, sans relay if the pump serves a single zone), then put a Taco 563-2 in series with that and the recirc pump.  Works even better with an occupancy sensor.

BigRob

Nice trick

I like that one. Not sure if I mentioned this is a 12 unit condo building with common hot water. We will try to automate as much as we can outside the units. The boiler is on the roof and the hot water line splits to 4 vertical bathroom/kitchen cluster branches, then all the branches connect on the ground floor and recirculate back up to the boiler. I may be able to install only 1 or 2 branch flow switches. I can install all the temperature sensors and pumps for all branches.

BigRob

Built In Thermostat

I really like model LHB08100108



http://www.pexsupply.com/Bell-Gossett-LHB08100108-Brass-Ecocirc-Circulator-w-Adjustable-Thermostat-Plug-1-2-Union



The built in check, ball, and thermostat are just what I need. I am thinking one unit for each branch in a potential quasi on-demand/timer based system. I can fit two flow meters easily and I think each flowmeter will cover half the building. When there is flow in either flowmeter, I will trigger a bank of pumps, which will then activate based on the built-in thermostats. Thoughts? I like this a lot. This way I don't have to worry about installing and monitoring branch thermostats - just need to activate some pumps with a zone controller or relays. Or the simple solution is just one flow meter and one pumps. We'll see.