Mixing

hot_rod

manual 3 way mix would track along with the OD reset control. For a little more $ you could addd some "smarts' in the form of a 3 way thermostatic. This would better regulate the temperature. I personally agree injection mixing would be over kill.

Or run both panels and radiant at 130 :) feed the panels first and the radiant take off from the P/S would probably be close to your need.

hot rod

Tom Hopkins

Mixing

Need suggestions as to options for mixing to reduce supply temperture for staple up radiant floor heat of two bathrooms. I have two zones with expansion room for 3 future zones.

Zone one is for a home run 8 panel radiator, for most of the house. This zone will have a supply temp of 140 degrees with a delta T of 30 degrees. Controlled by TRV's. The boiler (weil-mclain ultra with indirect) will be set to supply the 140 degree water. Will use ODR.

Zone two is for the radiant floor heat of the two bathrooms. Supply is through a 2 port manifold. Control will be via manifold zone actuators, each one controlled by a thermostat in the bathroom. My design calcs. show a supply temp of about 120 degrees for the radiant floors. I am having trouble determining what would be best for mixing setup to reduce the supply temp from 140 degree to 120 degree. Injection pump mixing seems overly complicated and expensive for a two loop radiant. Do not think that two balancing valves would do it properly. Which leads me to a three way thermostatic valve or a three way motorized valve. Any suggestions or thoughts?

The other three future zones would be for the shop (remote building w/fan coil), garage/basement (radiant) and possible expansion of the house (panel rads).

Piping is primary/secondary with the distribution piped in parallel. All is zoned by pumps.

Pete

tim smith

What about a Taco I valve??

Might be a relatively reasonable approach

Jamie_5

dumb mixing valve

If the ODR is controlling the temperature in the primary loop, why not use a "dumb" 3-way mixing valve on the radiant zone and let it ride the reset curve?

tim smith

Regarding fixed mixing

The issue I see is the thermostatic will maintain a constant outlet temp, so whatever the boiler is doing the mix valve will still maintain only one temp unless the boiler temp is below the setting of the thermostatic which won't be very often because the thermostatic is on the lower temp side of the system. jmho, Tim
I just re read your post, I would think you can get your temp requirements pretty close to same w/ design of emmitters to match water temp required. Tim

Tom Hopkins

thought about

thought about going as you said at 130 and then letting the downstream radiant go with whatever temp was left. I have sized the panel rads for 140 dgree supply, they are about as large as I would like to go with. They were starting to get too big when going with lower supply temp.

I would like to keep the radiant as simple as possible, as such I was thinking along your line with the 3 way. then as I read more I am seeing better control of mixed water temp with a 3-way thermostatic... then 3 way motorized.. them injection... Oh boy. I am over thinking all this?

Pete

Tom Hopkins

will look at it

Will look at it

Thanks Pete

tim smith

Response

As I said above, the I valve is a simple secondary reset valve that would get you the best of all worlds I think for the least. Just a thought.

Tom Hopkins

Tim and all thanks.

I have to get to a job site, so i will be back later.

Pete

Weezbo

you need to step back a long ways from your wallet...

Listen to what Hot rod said.

a simple three way mixing valve...i am not seeing any more control unless it would be to a lower temp than the return might offer...the 100 °
F top temp one from honeywell ,might quite likely be a better match. not to mess with your design parameters buh , just how often will the room need 120 water to meet design?

Tom Hopkins

what wallet

A 3 way is the way. Simple and not much of a problem for the wallet.

thanks to all