Radiant Design Help Needed - 5500 Sqft with 10 Zones

hevnbnd

So I have attached my heat load and loop layout. The plan is to install the boiler/Instant Hot water heater in the closet on the far North of the house. That would be the little room off the Master. I am a little confused on the how the Pex should be ran from the boiler to multiple manifolds. Do I have one manifold next to boiler with hot and return and run it to each additional manifold? So Main manifold next to the boiler would need to be a 4 port and it would run to the additional manifolds?

Any help on the design would be great. I really was not sure what to do with the hallways throughout the house. So I just expanded other zones to include the hallways and half baths. Think this is the best option or should I set those areas up as their own zone?

As for a pump I guess i am looking at one circulator pump. Possibly the Grundfos ALPHA2. Thoughts on this pump?

House is an ICF house with 2" foam under the slab. All pex will be in slab. Thought about adding an 11th zone in the small garage on the north side of the house.

Jamie Hall

Someone else will come in on this one, but I do have a comment... or two.

First, an instant hot water heater is not a boiler. It's not meant to be a boiler. It is, at best, a poor choice to power any hot water heating system, radiant or otherwise. You should use a boiler designed for heating.

Second, why so many zones? In my humble opinion, it would be much better to use far fewer zones and, if the room heat losses are really that variable, simply adjust the spacing of the lines or the flow (use balancing valves) to match the heat input of the system to the heat loss. So many zones are likely to give real control issues -- to little or no advantage.

Keep in mind that radiant systems are designed and intended to run all the time, with the temperature in the circulating water adjusted (usually, these days, with outdoor reset, perhaps trimmed by a room temperature or slab temperature sensor) to maintain the slab temperature at the needed value to counteract the space heat loss. They respond very very slowly (hours to days) to requested space temperature changes.

hevnbnd

Thanks for the reply. I will probably be using a wood-fired Hydronic furnace combined with solar for my heat source.

I attached new files with fewer zones.

GroundUp

Hate to be a stick in the mud here, but this is not a DIY system. A home this large with this many zones and variables, combining a solid fuel boiler with solar and it sounds like an electric or fossil fuel boiler also is out of the realm of possibility for most professionals, much less a DIY person. I'm not saying this to be a jerk, but you really need to consult with and pay a professional for a system design before you proceed. I admire your willingness to do the work, but it is absolutely necessary to have a professional design.

hot_rod

the next step is called a design, LoopCAD and other programs, possibly that Uponor program can do a tube layout and allow you to chose or move the manifold locations to optimize leader length.

It depends on the layout of the home, a sprawling rambler would require different manifold locations compared to a multi story.

Without knowing your skill level you may be competent to do the tube install and other work, hire a contractor to oversee or work along with you, many are open to leaving the grunt work to someone else. I've worked along with many of my customers on at least the tubing component.

And we have seen some top notch owner installs here over the years.

The multi heat source adds complexity, solar thermal ?? rarely pencils out on a hydronic system both $$ wise and actual contribution. In the sunny SW part of the US, possibly a 20- 30% contribution. If you are near Little Rock save the solar budget for PV.

hevnbnd

Well thanks for all the help. Lol. You guys are making a lot of assumptions... Like find a professional in your area.... Your assuming they exist. I know less than 3 people with hydronic systems in my area. They all did diy.

I am using solar on my roof. I installed 200 panels on my office. I am a licensed electrician. So I’m not totally helpless.

As for using LoopCad if you had looked at my attached docs you will see that my loops have been designed with LoopCad. I drew my plans with Revit so I know my way around cad programs.

hot_rod

Then LoopCAD should answer manifold placement.

Pex is not unlike wire, the shorter the distance between two points...

JacquesD23

I would do a manifold for each quadrant. Usually locate them in a closet wall with an access panel. For boiler efficiency if your doing a combi, I would want to know your shower/laundry schedule. Because most combis prioritize domestic. Which can get a little messy when you have as many zones as you do. To avoid this if you had to do a combi, I would recommend a larger tank style unit like the HTP Phoenix Multi Fit, or the Polaris (Now AO Smith) Tank style heaters.

Zman

Your software is doing some undesirable things. It looks like the delta of 20 is over riding everything else. This is giving you some very slow flow rates and random water temps. It also does not appear to be considering the length of the manifold distribution piping.

I would approach this much differently. I would design for a flow of ~.5-.75 per loop. I would establish a design day supply temp which would work for all loops(~ 120 degrees), the delta would be ~ 10 degrees.
I would then vary the tubing placement in each space to get the desired output and match the heat loss for that space.

You will need to look at the length of the distribution piping to the manifolds and determine what size it needs to be in order to achieve a reasonable pressure drop. This is very similar to the sizing of a feeder for an electrical panel, the farther you go, the bigger the wire.

I do not believe the Alpha 2 will be suitable. This is probably more like it https://www.tacocomfort.com/vr3452/index.html

GroundUp

hevnbnd said:

Well thanks for all the help. Lol. You guys are making a lot of assumptions... Like find a professional in your area.... Your assuming they exist. I know less than 3 people with hydronic systems in my area. They all did diy.



I am using solar on my roof. I installed 200 panels on my office. I am a licensed electrician. So I’m not totally helpless.



As for using LoopCad if you had looked at my attached docs you will see that my loops have been designed with LoopCad. I drew my plans with Revit so I know my way around cad programs.

Sounds like you have it all figured out then. Good luck!

hevnbnd

Clearly I don't have it all figured out that's why I asked for advise.

hevnbnd

Zman said:

Your software is doing some undesirable things. It looks like the delta of 20 is over riding everything else. This is giving you some very slow flow rates and random water temps. It also does not appear to be considering the length of the manifold distribution piping.

I would approach this much differently. I would design for a flow of ~.5-.75 per loop. I would establish a design day supply temp which would work for all loops(~ 120 degrees), the delta would be ~ 10 degrees.
I would then vary the tubing placement in each space to get the desired output and match the heat loss for that space.

You will need to look at the length of the distribution piping to the manifolds and determine what size it needs to be in order to achieve a reasonable pressure drop. This is very similar to the sizing of a feeder for an electrical panel, the farther you go, the bigger the wire.

I do not believe the Alpha 2 will be suitable. This is probably more like it https://www.tacocomfort.com/vr3452/index.html

Thanks for this information!

Paul Pollets

When I design this type of application I like to minimize zoning and only zone the desired room(s) by thermostat and telestat on the manifold loop. A boiler using ODR and constant circulation will keep the setpoint extremely accurate. Using a wood fired appliance will require a buffer tank, heat exchanger and correctly sized pumps. If nat. gas isn't available, my preference would be a propane mod-con with a low loss header to allow feed from alternate sources. Playing with the Manifold entry on the software design allows you to reduce loops or increase loop size to control head loss and keep it as low as possible. Better to have more loops at shorter length than long loops. The best design hinges on the "near-boiler" piping and control strategy. You've done a good job on the loop layout.

hot_rod

I'm not that well versed with the program you are using. I have seen experienced designer get into that program and change or adjust defaults. Like any software it is only as good as the inputs.

If you have a local rep nearby it may be worth getting a second opinion.

There are several designers that hang around here that could also work over you load and design. There is some time commitment involved to optimize a design, it may be worth the time or money spent to get this important first step as good as possible.

kenjohnson

I'm a homeowner and diy'er. I modeled and designed my own system using information I learned here and on other sites, and got some very relevant feedback here. My system is installed and is working great. A link is here https://forum.heatinghelp.com/discussion/163346/would-like-some-feedback-on-my-radiant-design-plans#latest

A couple comments:
1. I used the Grundfos Alpha2 pump, It works for me, but I have a lot smaller house. It puts out I think 4 gpm max for me with 9 loops and I think about 12 feet of head (calculated, from memory). You should look at the pump curve for it - I think you'll learn pretty quickly that this won't work for you.
2. You'll probably need to iterate your design several more times.
3. A lot of loops isn't a bad thing - you want to equalize loop lengths as much as possible. With some long lengths of PEX just to get to the beginning of some loops, I would think you would want to insulate the supply of those loops really well and/or install some type of larger pipe to supply a manifold closer to the beginning of those loops.
4. You should be thinking about how you are going to sense and regulate temperature in each room.

If you are going to use a wood-fired boiler, I would be digging around hearth.com for some advice - go to the Boiler Room forum and check that out.