closely spaced tee's

Timco

Would either of these layouts look like a better option? I a always open to suggestions.

Thanks for the word,

Tim

Timco

Is there a minimum distance between secondary zones along the primary loop?

Tim

Brad White_141

Do you mean between

the tees on the secondary loop (or on the primary loop for that matter) or do you mean between opposing tees on the opposing loops?

The former, tees on the same circuit, want to be as close as possible. Butted if you can and not over 4D appart in any case, ideally.

Also keep them about 8D away from adjacent elbows and other tees. (This may be, come to think of it, exactly what you are asking!)

As for the space between the circuits, the bridge piping? No minimum that I know of, just enough to accomodate your valve train, injection circulator or whatever you are using to meter circuit #1 water into circuit #2 water.

Timco

That is what I was asking. I know about the closely spaced tee's, but did not know how far apart to space the 'sets' of tees from each other.

Thanks again!

Tim

Brad White_141

Took me a minute, Tim

but I get there eventually! I figured you of all people knew the other parts but left them in the response because I had already typed them and just to be sure....

Now, on top of this, I am sure you know that as you are setting this up that way, there will be a cascading reduction in temperature, diluting the downstream zones. You do have multiple temperatures in mind, don't you? Just have to ask.

Brad

Timco

Actually, I have 3 zones that feed all CI rads, and one indirect zone. I chose the p/s piping to act as my bypass and feed all 4 zones equally. Indirect will be fed first, with full size tee's (11/4). Figured my primary GPM @ 16...thus the 11/4.

Tim

Brad White_141

So...

It is really parallel P/S rather than series?
Coming off bridges across supply and return on the primary side? That will give each circuit the same temperature.

I am a tad more conservative in that I use 1-1/4" up to about 10 GPM, maybe 12. Then I go to 1-1/2" up to 18-20 GPM. But that is just me No criticism intended.

Cheers!

Brad

Timco

The indirect is parallel, but the rest is standard p/s. See crude scetch...

Tim

Unknown

that's look like the

That looks like the system I installed with 5 temps zones with 3 way mixing valves.. But no dhw zone.... Should there be a checkvalve on the return of dhw zone to keep the primary pump from going into return of dhw. Is the reducing or balencing valve needed on the supply of primary loop?

Timco

As I understand it, the check goes on the primary loop return, not the DHW zone. I drew the balance valve in because I have not looked up the flow chart on the 007 that will be running my primary loop. Looking for 16 GPM with 25' or so of 11/4" with 4 90's.

Tim

TK03

Piping

Your choice of piping is not the best as all radiation will not receive the same water temperature. Primary/secondary does not do alot for boiler protection, especially with large water volume systems. Use a manifold system with a boiler bypass pipe (cold return to hot supply, Primary loop with small manifold for all supplies and returns off a primary loop with a boiler bypass, or straight primary pipe with all supplies on one side and all returns on the other. Boiler tied in with close spaced tees between supply and return pipes and boiler bypass.

Brad White_141

#1

is more of a P/S layout. #2 is more of a conventional layout with bypass.

In #2, the circulator moving CCW being the bypass, really only wants to protect the boiler (I am assuming CI not a ModCon).

If that is the case, one of the variable speed Taco's being concurently discussed may have an application here, responding to the boiler HWR temperature. Just be sure that the building return enters that circuit well ahead of the boiler so there is time to mix with the bypassed hot water.

Your #1 is more of a parallel P/S setup. I would take the DWH boiler return into the line after the building return to give it some time to mix. When it goes directly back to the boiler (CCW as you show) a slug of cold water could enter the boiler without any tempering, especially if the heating zones are not calling.

An alternative to #1 is the cross-tree layout I described last night. Sorry I cannot post a sketch right now, but it is a series of bridges from the top supply to the bottom return.

Within these is a balancing valve on the return. Off of each of these bridges is a pair of closely spaced tees from which you circulate to your radiators.

All see the same temperature and the balancing valve keeps the bypassing to the return to a minimum. When you throttle the balancing valve on the return side of the bridge below that circuits' radiation flow rate, there is some recirculation in the bridge tees, reducing the radiator output temperature.

Timco

Brad...

Thanks soo much for your time & input. This will be my first p/s job. I typically use the direct return (#2). Is this sketch what you were thinking? Does the end of the pri just cap as shown? How do you set the balance on the bridges? By temp?

Tim

Timco

Would the pri circ always come on even with a DHW call? This is the boiler protection?

Tim

Dave Holdorf_2

Primary Circ

The primary circ should come on when only there is a heat call. For DHW, primary should be off so that there is no wasted heated through the primary loop in the summer.

I like sketch 1, all zones get the same water temp.

Brad White_9

That is the one, Tim

Personally, I would run the primary circulator all the time (except if your boiler is a ModCon) based on outdoor temperature. Adjust your setpoint to what your actual profile is. Sometimes even as low as 55 versus 65 in some systems. A simple Ranco controller does mine at home.

Thus you are always ahead of a heat demand. If any short cycling occurs as it can on low load, a buffer tank may serve you well. Many options, I hope not too many.

For tempering the DWH side, a bypass on the DWH would suit me fine any time of the year. But the essentials are there.

tk_3

Sketches

I agree sketch is good as all the zones get the same water temperature but I see no real boiler protection. Again Primary/secondary is not true boiler protection. Whatever the return water temp drops to when these zones open is what goes to the boiler. Cast iron and steel boilers work best with a boiler bypass. Sketch 2 shows a system bypass. In todays residential cast iron boilers it is important to control flow through the boiler. The system bypass increases flow through the boiler thus less water temp increase and longer condensing state. More rust and acid damage. Other advantage's to boiler bypass is heating less water volume and only heating the loops to a temperature required to satisfy the thermostat.

Timco

Soooo

Thanks soo much for all input. Do we like sketch 1 or 3 (the last with the parallel bridges) best? LEaning towards sketch 1, but like 3. Which is best?

Tim

Timco

I put a new sketch on 'piping plan approval needeed' post. Will it fly?

Tim