Radiant floor zones & pumps

Marvin007

If I have a 10 zone (between joist) manifold and each zone has max of 300 ft of 1/2 PEX for a total max of 3000ft. What determines the size of circulation pump and how many pumps are required?

psb75

You don't have 10 "zones". You have ten ports on the manifold which indicates 10 separate loops of heating pex in the floor. It then depends on if you want to divide areas of that 3000 ft floor into separate zones. Each zone needs a circulator and a thermostat. Best thing is to minimize number of zones. Circulator size is based on your longest loop in that zone--which you say is 300'.

Dave H_2

The first thing that is needed is not just the number of loops, but it is based upon the heat loss of the area being heated.
With that being said, 1/2" pex in radiant floor applications usually has a flow rate of around 0.5 gallons per minute for a total flow of 5 gpm for your system.
Then based upon the heat loss and then the flow needed in each loop as well as required water temperature, we use the head loss charts based upon the loop length. Being under 300' long, pex manufactures suggest that as a max to use typical residential sized circulators.

Marvin007

Thanks I don’t have 10 zones. I asked this question in order to get a simple answer. Thanks for the replies. 

So a variable speed zone pump seems to take up the least amount of wall space and have the least amount of parts to break/maintain.

Anyways I have a rough design of what I would like to build. I don’t want to overcomplicate my design. I also don’t want to over simplify it and have a non working system.

This is a renovation. In my design I have 12 loops each being approx. 220 - 300ft max of 1/2” pex. I would like 5 zones. 3x zones underfloor between joists and 2x zones running at a higher temperature for baseboards. My biggest zone consists of 4 loops about 1000ft of pex.

Hot_water_fan

Not sure why you have 10 loops of equal length, unless it's a big open plan layout. Otherwise, it's a waste of PEX.

Can you elaborate? How is it a waste of pex? Is it a meaningful waste of pex? 300’ per loop seems rather standard to me at this diameter. 

hot_rod

.65 gpm per loop would be on the high side of what is commonly designed.

So at .654 for a 300' loop of water, you have around 4.5' head

So that is the head. the gpm is total of all the loops, 10 loops at .65 gpm= .6.5 gpm

Sop that is the pump spec. Any brand of the small ECM will do, get one with multiple speeds so you can adjust some if needed.

In a perfect design you would know the heat load of each zone, which tells you the gpm required, so you may only need .50 gpm, but since the pumps have adjustability figure the high number of .65 gpm.

So with a 2 temperature system you need some sort of mixing device, so to calculate the circ for that zone or zones we need to know what valve you are using. I suspect the same size circ will work. But an exact answer would require more info.
Grundfos Alpha 15-55, Taco 007E, same size available from B&G, Wilo, Armstrong, and a few others.

Marvin007

What is type of mixing valve is best to be used in a 2 temperature radiant system? Thermostatic?

Paul Pollets

A 3 way valve with motor actuator is often used. The motor connects to the boiler control and should automatically adjust temperature setpoint

Marvin007

Paul Pollets said:

A 3 way valve with motor actuator is often used. The motor connects to the boiler control and should automatically adjust temperature setpoint

What is the technical name for this valve? Will this valve connect to a Navien Combi Boiler or will it connect to a zone control panel which connects to the Navien Combi Boiler?

hot_rod

So 6.5 gpm is the total flow for all the radiant zones?  That is a bit high for a typical 1” thermostatic mixing valve

A motorized mix valve would have better flow and the ability to use an outdoor reset function
Taco has a 3 way valve with the reset function onboard. Tekmar, Belimo, Danfoss are some other brands
Most all the radiant manufacturers have a valve or mixing block available.

Viega has a mixing assembly with a circulator included, and the control

Marvin007

hot_rod said:

So 6.5 gpm is the total flow for all the radiant zones?  That is a bit high for a typical 1” thermostatic mixing valve

A motorized mix valve would have better flow and the ability to use an outdoor reset function
Taco has a 3 way valve with the reset function onboard. Tekmar, Belimo, Danfoss are some other brands
Most all the radiant manufacturers have a valve or mixing block available.

Viega has a mixing assembly with a circulator included, and the control

Is this the most expensive option? What is a moderately priced option?

Marvin007

I have a rough design of the piping to the manifolds and how it would be layed out on my 2 basement walls. Is it acceptable to place the expansion tank and the combo boiler this far away from the manifold? I am really tight for space. The reason that there is 1 extra loop for Zone 1 and Zone 2 in Option 1 is because I will need to add them in order to keep my loops under 300' and run them all to the center of my basement.

I would much rather keep all of the loops central to the center of my basement but this means I would have 22-24 1/2' pex pipes coming together on this small wall. I have my ceiling dropped 1-1/2" down the center of my basement already. Does running all of my pipes to the center of my basement seem like a bad idea because of the limited space or does it look doable?

Do I only need 1 mixing valve for the lower temperature (Temp#2) manifold (between Joists loops)?

Am I missing any other components?

HomerJSmith

You don't need a ECM (variable speed) pump unless you have Thermo-actuators on the manifold. I'm assuming that you want a pump on each manifold? How many thermostat do you have?

Also, do you have flo gages on each loop of a given manifold? If all the loops on a manifold are within 10% in length, then the pressure loss in each loop is about equivalent then flo adjustment valves aren't necessary.

Marvin007

HomerJSmith said:

You don't need a ECM (variable speed) pump unless you have Thermo-actuators on the manifold. I'm assuming that you want a pump on each manifold? How many thermostat do you have?

Also, do you have flo gages on each loop of a given manifold? If all the loops on a manifold are within 10% in length, then the pressure loss in each loop is about equivalent then flo adjustment valves aren't necessary.

I have not built a system like this before and know only what I do from my extensive research and talking to others for the past 10 months. Do I need a pump on each different temperature main manifold or could I use 1 for the whole system and place it in a different location? I am planning on putting actuators on all zones. If I select Option 1 the 12 loop Manifold I would need 12 actuators + 2 for the panel radiator zones in order to control the correct loops for each zone via a thermostat for each zone. If I select Option 2 I could use 5 actuators...1 for each zone.


Flo adjustment gages would be on the manifold I end up buying.

hot_rod

If you have actuators on all the manifolds. A single ECM delta P circ is ideal

Since you have a low temperature zone, that needs a mix valve and pump

A thermostatic is usually the least expensive automatic control. You want one with a 5 Cv or higher

A manual 3 way mix valve could be used, try getting it adjusted on a cold day.  If it doesn’t perform to your liking, add a motor and control later.

Or a manifold with the thermostatic mix valve built in.

Just depends on what you want to spend and how much control you want.

HomerJSmith

Is this still in the planning stage, you still have to buy everything? There is a problem in using one pump for all the manifold cabinets. The way it works is that the greatest flo goes thru the shortest run. You would have to balance the flow to each manifold so each manifold would get the same flo rate. Then each loop on the manifold if they are about the same length would need a flo of between .5-.75 GPM. I prefer something like Caleffi Fixed Point Manifold Mixing Station.https://www.supplyhouse.com/Caleffi-1725F1A-Fixed-Point-Manifold-Mixing-Station-w-UPS-15-58-Pump-6-Outlets
You can probably do it cheaper with individual pump on each manifold.

hot_rod

Are you feeding remote manifolds for other manifolds? Just be aware of the available gpm from the ports of a manifold.

You shouldn't need a mix valve on the radiator loop? Just run the boiler at that required temperature ODR even. Then mix the radiant zone.

Here is an option, I like using a hydro sep, you get air, dirt, mag, and hydraulic separation from one device.
The boiler has a pump onboard if it is a combi.

Chose whatever mix valve you want for the radiant.

I prefer all the pumps near the boiler for service, leaks, etc. Both should be ECM if the manifolds have actuators.

Marvin007

hot_rod said:

If you have actuators on all the manifolds. A single ECM delta P circ is ideal

Since you have a low temperature zone, that needs a mix valve and pump

A thermostatic is usually the least expensive automatic control. You want one with a 5 Cv or higher

A manual 3 way mix valve could be used, try getting it adjusted on a cold day.  If it doesn’t perform to your liking, add a motor and control later.

Or a manifold with the thermostatic mix valve built in.

Just depends on what you want to spend and how much control you want.

What is the difference between these 4 manifolds... Fixed / Fixed Inverted, UPS-15-58 / Alpha-25-55U?
Which one would work best for my setup?

https://www.supplyhouse.com/Caleffi-1725N1A-Fixed-Point-Manifold-Mixing-Station-w-UPS-15-58-Pump-12-Outlets
https://www.supplyhouse.com/Caleffi-1725N1A-INVERTED-Fixed-Point-Manifold-Mixing-Station-w-UPS-15-58-Pump-Inverted-12-Outlets
https://www.supplyhouse.com/Caleffi-1725N1AHE-Fixed-Point-Manifold-Mixing-Station-w-Alpha-25-55U-Pump-12-Outlets
https://www.supplyhouse.com/Caleffi-1725N1AHE-INVERTED-Fixed-Point-Manifold-Mixing-Station-w-Alpha-25-55U-Pump-Inverted-12-Outlets

Marvin007

HomerJSmith said:

Is this still in the planning stage, you still have to buy everything? There is a problem in using one pump for all the manifold cabinets. The way it works is that the greatest flo goes thru the shortest run. You would have to balance the flow to each manifold so each manifold would get the same flo rate. Then each loop on the manifold if they are about the same length would need a flo of between .5-.75 GPM. I prefer something like Caleffi Fixed Point Manifold Mixing Station.https://www.supplyhouse.com/Caleffi-1725F1A-Fixed-Point-Manifold-Mixing-Station-w-UPS-15-58-Pump-6-Outlets
You can probably do it cheaper with individual pump on each manifold.

Yes, this is still in the planning stage.

I understand the problem you have pointed out in Option 1 (drawing) regarding the flow rate between the 2 main manifolds (Temp 1 & Temp 2). I will need to fix this. What type of device should I add to balance the flo and where should I put it?

Since I want the system to be as simple as possible least insulation/maintenance. I think using the Caleffi 1725N1A or 1725N1AHE might be a good option.

I will update by drawing by making the changes and repost it.

Marvin007

hot_rod said:

Are you feeding remote manifolds for other manifolds? Just be aware of the available gpm from the ports of a manifold.

You shouldn't need a mix valve on the radiator loop? Just run the boiler at that required temperature ODR even. Then mix the radiant zone.

Here is an option, I like using a hydro sep, you get air, dirt, mag, and hydraulic separation from one device.
The boiler has a pump onboard if it is a combi.

Chose whatever mix valve you want for the radiant.

I prefer all the pumps near the boiler for service, leaks, etc. Both should be ECM if the manifolds have actuators.

I was thinking about feeding remote manifolds in Option 2 drawing but I don't really want to hide remote manifolds around my house in main floor closets...possible leaks and flooding. I think keeping all manifolds and loops on one Wallin the basement is probably best for maintenance and preventing any possible future leaks. The I will probably have to redesign all of my loops in order to incorporate 2 more loops so that all my 12 loops will be under 300 and reach to the center of the house. That is ok.

I noticed I am missing some kind of water/debris filter. Which one should I use or is this what you meant by adding a hydro sep?

Is a hydro sep a nice to have but not required? Does this prevent rust and other debris from rusting the combo boiler?

If I use a hydro sep I don't need a separate air separator on top of the expansion tank? Where would I place the hydro sep in my setup?

I will update by drawing by making the changes and repost it tomorrow.

Navien combi boilers have a builtin pump. Is this enough to drive my two manifolds: Temp 1 (3 loops), Temp2 (12 loops - Caleffi - Fixed Point Manifold Mixing Station)?

Does the Caleffi - Fixed Point Manifold Mixing Station have a builtin back flow preventer and a builtin circulation pump?

hot_rod

Looks like Navian is encouraging primary secondary piping and optional mag filter. I doubt the onboard pump has enough capacity to pump your system.

A Sep 4 for example does all the functions in one device, makes the piping easy and really isn't much more $$ then just that header assembly. So the boiler pumps to and from the sep. Separate pumps for the zones are required.

So you need either their option header, build your own, or use a hydrosep.

Same concept with those preassembled manifolds, all the right components in the correct location. Much easier than building your own.

Pros and cons to manifold locations, as you discovered you burn a lot of tube getting to and from remote rooms when manifolds are in the mech room. You need to find a place to route the tube, and that will be a very warm space It is really installer preference.

Use the 172 with the ECM pump option if you plan on using zone actuators on the manifold.

Inverted manifolds have the ports facing up instead of down to save some tube and clean up the boiler room piping.

Marvin007

hot_rod said:

Are you feeding remote manifolds for other manifolds? Just be aware of the available gpm from the ports of a manifold.

You shouldn't need a mix valve on the radiator loop? Just run the boiler at that required temperature ODR even. Then mix the radiant zone.

Here is an option, I like using a hydro sep, you get air, dirt, mag, and hydraulic separation from one device.
The boiler has a pump onboard if it is a combi.

Chose whatever mix valve you want for the radiant.

I prefer all the pumps near the boiler for service, leaks, etc. Both should be ECM if the manifolds have actuators.

What does Exp mean in your hand drawn sketch?

Marvin007

Do I definitely need a 3rd pump or will the primary circulation pump builtin to the Navien possibly be enough to supply the panel radiator manifold and feed the Caleffi 172 series 12 port manifold?

I called Caleffi and they said that the 172 Series manifold comes with a pump that will be sufficient to circulate the water through the 12 loops.

Here is my updated design. I have added shutoff valves in different areas incase I need to be able to remove or service specific parts. Is this a good idea or a waste of time and money?

What type and size of expansion tank should I use?

hot_rod

Don’t you want a two temperature system, panel rads typically run higher temperature than the radiant? That is what the first drawing shows.
Do you have a design that indicated the water temperature needed?

If you want or need two temperatures then either primary secondary, the Navian header, or a hydrosep

If it is a single temperature system and you use that Caleffi 172 it has a small separator built into it.

Exp for expansion tank

Marvin007

hot_rod said:

Don’t you want a two temperature system, panel rads typically run higher temperature than the radiant? That is what the first drawing shows.
Do you have a design that indicated the water temperature needed?

If you want or need two temperatures then either primary secondary, the Navian header, or a hydrosep

If it is a single temperature system and you use that Caleffi 172 it has a small separator built into it.

Exp for expansion tank

I do want a two temperature system. The difference from the original drawing Option 1 and Option 3 above is that I flipped the position of the manifolds on the wall. This will make it easier to run the pex to the larger manifold. Since the larger manifold is the Caleffi 172 and comes in an inverted version. Now I can run the between radiant floor joist pex loops from the ceiling down the wall directly to it.

I do not have a design with the water temperature needed for the radiant floor joists pex. What is an approx. temperature that is typical to run radiant floors?

I have calculated my panel rads to run at 160F. If I select larger rads I could drop it to 140F.

Do I need to balance the source flow between the two different temperature manifolds? If so what type of valve should I use for this?

hot_rod said:

If you want or need two temperatures then either primary secondary, the Navian header, or a hydrosep

I'm not sure I understand what you mean by getting two temperatures out of the radiant boiler side of the Navien header or how a hydrosep would do this? If I misunderstood you don't bother elaborating. I understand everything else you have told me.

hot_rod

Without any flow data, it’s a bit of WAG
5 or 6 ways you could pipe it, this option gives you the most flexibility 

Connect the boiler directly to a 1” hydrosep, 1” copper piping from the boiler No additional air purger or dirt separator needed, it’s in the Sep

on the opposite side, still 1” copper 1st  a pump for the panel rads. This will run at the same temperature as the boiler 160 or??  Use the ODR function on the boiler

A 12 port manifold will need at least 6 gpm, 3/4 Pex may not cut it, 1” to the 172 location

3/4 may be enough for the panel rads. How many, what is the total btu rating?

You need 3 pumps, the boiler pump is not adequate for the panel rads

So the boiler pump included in the boiler

A pump for the panel rads Grundfos 15-58 or 15-55

The 3rd pump for the radiant is included with the 172

I have mounted a boiler and hydro Sep on a 48” wide panel. If that is a requirement?

Radiant can run anywhere from 90f to 140f depending on the heat load of the various rooms. It will be trial and error worth out design info. If you used aluminum transfer plates I’m guessing 115- 120f. Hopefully no carpet areas? That drives up the required supply temperatures 

Marvin007

hot_rod said:

Without any flow data, it’s a bit of WAG
5 or 6 ways you could pipe it, this option gives you the most flexibility 

Connect the boiler directly to a 1” hydrosep, 1” copper piping from the boiler No additional air purger or dirt separator needed, it’s in the Sep

on the opposite side, still 1” copper 1st  a pump for the panel rads. This will run at the same temperature as the boiler 160 or??  Use the ODR function on the boiler

A 12 port manifold will need at least 6 gpm, 3/4 Pex may not cut it, 1” to the 172 location

3/4 may be enough for the panel rads. How many, what is the total btu rating?

You need 3 pumps, the boiler pump is not adequate for the panel rads

So the boiler pump included in the boiler

A pump for the panel rads Grundfos 15-58 or 15-55

The 3rd pump for the radiant is included with the 172

I have mounted a boiler and hydro Sep on a 48” wide panel. If that is a requirement?

Radiant can run anywhere from 90f to 140f depending on the heat load of the various rooms. It will be trial and error worth out design info. If you used aluminum transfer plates I’m guessing 115- 120f. Hopefully no carpet areas? That drives up the required supply temperatures 

I reaIly appreciate your help and everyone elses. I have redesigned my loops and condensed them down to 8. I would like to have 2 or 3 spare on my manifold so I think I can use a 10 or 11 loop manifold now.

I would like to confirm a few things:

1. Is where I placed the hydrosep to high? Should it be placed below the combi boiler?
2. If I use a 10 port manifold do I need 1" copper to supply it?
3. If I use a 11 port manifold do I need 1" copper to supply it?
4. Can the 27' section of 1" copper pipe for the return and supply lines running between the the combi boiler wall #1 and manifold wall #2 be 1" PEX and converted to 1" copper at each end when it reaches the wall?...Copper is expensive but I don't want any issues with the performance of the system so if there is a reason I should use copper then I should.
5. Is 300ft max joist loops good for my loop sizes or should they be closer to 250ft?
6. Two of my loops are much shorter than 300ft: Loop 2 is 269', Loop 4 is 205'. Should I make them closer to 300 and hide the extra pex in the ceiling in order to better balance the loops?
7. I have placed the 3 port rad manifold below the radiant floor joist manifold on the wal is this OK? I have done this because I might want build the between floor joist manifold and loops first to test the system for heat output before buying too many expensive panel radiators that I might not require. There might be enough heat in some of the basement rooms from the radiant pex pipes in their ceiling.
8. What is the square in your drawing beside fill? please see the picture.
9. What size of expansion tank do I need?
10. If I only build Phase 1 (the radiant between joist manifold) to start do I still need to install the 3rd pump or can leave this pump out until I install phase 2 at later date?

hot_rod

The sep could mount anywhere on the wall, below, or above the boiler connections. It does not need to be a high point. The supplies, your red lines I assume? need to be on the top of the sep, not bottom.

As for pipe size. Ideally we need the gpm requirement of the loops. .50- .65 is commonly used for 1/2" pex loops.

So 10 loops at .50 gpm you need 5 gpm

If you want to use pex, go to the PPI website and enter the data you know, length of run, back and forth, fluid temperature. Fittings like 90 ells add about 5 feet each, so add fittings into the calculation. Here are 3 examples of pex and one for copper.

# note uses the temperature you are running for both manifolds in the calculation. Mine were room temperature examples.

You are kinda tight with 3/4, not knowing the exact length with fittings. And if you did need to run more flow, .65 gpm you are beyond 3/4' pex range. I'd use 1" pex or 3/4 copper. But run your own numbers. The calculator is free.


Find copper tube calculators at engineeringtoolbox.com.


The red box shows the expansion tank and fill valve assembly.

With your piping as drawn you will need to run the pump shown on upper right and the 172 pump to get radiant. You would need zone valves, zone actuators or TRVs on each radiator to prevent them from heating when the 15-58 is running for the radiant the high temperature.

Why not the 15-58 back at the sep like the drawings I suggested? It would require 4 runs of pex. Two for the 172, two for the panel rad manifold. Then the 15-58 only runs for panel rads

Use two of these Webstone valves at the Sep connections and the entire system could be purged in the mechanical room.

Marvin007

Is a purge valve also a shutoff valve?

hot_rod

The high temperature manifold wouldn't need to be at the separator where the circulator is located. Remote mount it, if that helps keep the pex loop runs shorter?

I'd like to see the expansion tank connection right at the sep. The tank could mount anywhere in the room, but the connection into the system should be close to the separator. If it is easier to mount the tank elsewhere in the room, just run 1/2" pex from the tank to a connection at the sep.

That Webstone valve is a shut off and purge valve all in one.

Marvin007

Do either of these look proper?

hot_rod said:

The high temperature manifold wouldn't need to be at the separator where the circulator is located. Remote mount it, if that helps keep the pex loop runs shorter?

I'd like to see the expansion tank connection right at the sep. The tank could mount anywhere in the room, but the connection into the system should be close to the separator. If it is easier to mount the tank elsewhere in the room, just run 1/2" pex from the tank to a connection at the sep.

That Webstone valve is a shut off and purge valve all in one.

Marvin007

hot_rod said:

The high temperature manifold wouldn't need to be at the separator where the circulator is located. Remote mount it, if that helps keep the pex loop runs shorter? I'd like to see the expansion tank connection right at the sep. The tank could mount anywhere in the room, but the connection into the system should be close to the separator. If it is easier to mount the tank elsewhere in the room, just run 1/2" pex from the tank to a connection at the sep. That Webstone valve is a shut off and purge valve all in one.

What are some decent hydroseparators I could use? I would require a 1” version correct?

hot_rod

Marvin007 said:

hot_rod said:

The high temperature manifold wouldn't need to be at the separator where the circulator is located. Remote mount it, if that helps keep the pex loop runs shorter?

I'd like to see the expansion tank connection right at the sep. The tank could mount anywhere in the room, but the connection into the system should be close to the separator. If it is easier to mount the tank elsewhere in the room, just run 1/2" pex from the tank to a connection at the sep.

That Webstone valve is a shut off and purge valve all in one.

What are some decent hydroseparators I could use? I would require a 1” version correct?

Yes, 1"
Look for a model that has the 4 or 5 functions.
SupplyHouse has choices. If you are near a FW Webb, they have a 5 in 1.

Marvin007

So for the closed loop 2 temperature system above, using all 1/2” HelioPEX for the radiant floor loops and for the 2 Rad loops (baseboard/panel radiator) is a correct option?