Radiant Floor Design Critique

flyingmeatball

I'm about to get started setting up the mechanicals for my radiant floor system and was hoping to get some feedback/critique before I start installing in the new couple of days. The manifolds are already in place and the concrete is poured over the pex tubing (no going back now!).




Key Components:
Navien NHB 80 boiler (heat load is ~60K Btu/H)
circulators: Grundfos UPS15-58FC
Manifolds: Caleffi 1" brass twistflow manifold (6686)
Dirt separator: caleffi 1" Sweat 5463 Series DIRTMAG Dirt separator with magnet
Air Separator: Watts 1" Cast Iron Air Separator (0950313)
check valves: 1" spring-loaded check valves following each circulator, 1" Watts lead-free dual check valve for make-up water

For comparison, here's what the Navien manual showed for a similar setup:



Questions I had:
Is my primary/secondary done correctly? I saw a bunch of variations of where to place the expansion tank/air separator/make-up water apparatus. Similarly, I went back and forth on whether the primary circulator should be on the supply or return side of the boiler, but kept it return because that's where it was in their install manual.
Are my fill/drain valves placed correctly? It took me a while to get to the placement of those - if I'm missing anything that will make emptying/filling the system difficult please let me know.
Is the dirt mag in the right spot? I heard to put it in the primary loop and as low as possible...so that's what I did.

neilc

with the concrete poured, it's late to ask,
but,
what's your loop lengths, and tube size?

Snowmelt

All looks good let’s see the real deal

SuperJ

I would move the dirtmag to the secondary before the boiler return tee. That way all the flow will go thru it giving you maximum effectiveness.

I would skip the cast iron air scoop, and use a proper microbubble air separator.

At 60kbtu heat load it's likely you could use a single delta p circulator and zone valves, saving some power.

For you primary secondary arrangement, you need to make sure your headers are big enough to avoid flow interactions.

I think the grundfos pumps come with a check valve they can be field installed into the discharge of the pump. It has the advantage of having a minimal effect on pump performance.

Snowmelt

I would get the 4 in 1, air sep, mag, dirt sep and hydronic separator all in one.

Gordy

Install the dirt mag on boiler return upstream of the boiler loop circulator is the best location. That way any impurities in the system are captured before they reach the boiler, and associated circ on initial commissioning of system. Also the dirt mag is more efficient in lower flow regions. If set up properly the boiler loop flow rate should be less than system flow rate.

Zman

You added a bypass valve on the secondary. I can't visualize a time when you would want that open. Otherwise, looks good.
Good suggestions above as well.

hot_rod

A 4 in 1 hydro sep would clean it up and give you 4 functions in one box.

If you use that schematic, I move the expansion tank to the left of the close tees.

flyingmeatball

Thanks all for the constructive comments.

@neilc - I have ~2300 ft of 1/2" pex tubing - one manifold has 4 loops at ~180 ft, the other has 8 loops at ~210 ft

@SuperJ - good suggestions all around - 12 actuators was going to cost a lot more than 1 extra grundfos pump, so I went that route. I know I'll pay for it over time in power, but my wife is less likely to scrutinize the electric bill vs. the plumbing supply receipt . Noted on the microbubble - will change that. Can you elaborate on the header comment a bit more? I'm using 1" copper pipe into a 1" manifold, I thought that was going to be plenty big for the system I had...The check valves would have been a good idea, but I'm too lazy to RMA the ones I have/reorder.

@snowmelt @hot rod_7 - good suggestion, and surely the "correct" way to go. I'm going to go with what I've got for the sake of learning/not having to return stuff though. Takes the "fun" out of figuring out what the parts do/how they work.

@Gordy @SuperJ - Two conflicting options on dirtmag location,
current setup logic: dirtmag is in lowest point of system with the lowest flow - dirt is likely to accumulate here. The boiler circ is indeed upstream of the dirt mag, but if I put the dirt mag first, the circ ends up at the lowest point of the system - install instructions say, " Do not install the pump at the lowest point of the system where dirt and sediment naturally collect."
Different Option 1: put the dirtmag on boiler return before pump. This results in boiler circ being at lowest point in system - is it better to have the dirt mag first, even if it means putting circ down here?



Different Option 2: Move dirtmag on secondary upstream of boiler return. This means water will be flowing faster when it hits dirt mag, but everything will flow through it, vs just the water returning to the boiler. This also isn't the lowest point in the system - which is better, the slow water at lowest point, or filtering all of the water?



@Zman - I thought there might be some fill/purge scenario where I'd like to have the full secondary loop running without going through a zone. If that would never happen I can remove, but I was trying to be safe rather than sorry. I've seen some versions as well that have pressure bypass valves there - is that not a concern at all for future expansion/troubleshooting?


Thanks all for your input - much appreciated!

Solid_Fuel_Man

You could use zone valves with one circulator if you have the two manifolds for 2 zones.

flyingmeatball

Solid_Fuel_Man said:

You could use zone valves with one circulator if you have the two manifolds for 2 zones.

actuators are ~$60 a pop, 12 of them is ~$720. A grundfos pump is ~85, or so.

SuperJ

> @flyingmeatball said:
> Thanks all for the constructive comments.
>
> @neilc - I have ~2300 ft of 1/2" pex tubing - one manifold has 4 loops at ~180 ft, the other has 8 loops at ~210 ft
>
> @SuperJ - good suggestions all around - 12 actuators was going to cost a lot more than 1 extra grundfos pump, so I went that route. I know I'll pay for it over time in power, but my wife is less likely to scrutinize the electric bill vs. the plumbing supply receipt . Noted on the microbubble - will change that. Can you elaborate on the header comment a bit more? I'm using 1" copper pipe into a 1" manifold, I thought that was going to be plenty big for the system I had...The check valves would have been a good idea, but I'm too lazy to RMA the ones I have/reorder.
>
> @snowmelt @hot rod_7 - good suggestion, and surely the "correct" way to go. I'm going to go with what I've got for the sake of learning/not having to return stuff though. Takes the "fun" out of figuring out what the parts do/how they work.
>
> @Gordy @SuperJ - Two conflicting options on dirtmag location,
> current setup logic: dirtmag is in lowest point of system with the lowest flow - dirt is likely to accumulate here. The boiler circ is indeed upstream of the dirt mag, but if I put the dirt mag first, the circ ends up at the lowest point of the system - install instructions say, " Do not install the pump at the lowest point of the system where dirt and sediment naturally collect."
> Different Option 1: put the dirtmag on boiler return before pump. This results in boiler circ being at lowest point in system - is it better to have the dirt mag first, even if it means putting circ down here?
>
>
>
> Different Option 2: Move dirtmag on secondary upstream of boiler return. This means water will be flowing faster when it hits dirt mag, but everything will flow through it, vs just the water returning to the boiler. This also isn't the lowest point in the system - which is better, the slow water at lowest point, or filtering all of the water?
>
>
>
> @Zman - I thought there might be some fill/purge scenario where I'd like to have the full secondary loop running without going through a zone. If that would never happen I can remove, but I was trying to be safe rather than sorry. I've seen some versions as well that have pressure bypass valves there - is that not a concern at all for future expansion/troubleshooting?
>
>
> Thanks all for your input - much appreciated!

I like option 2 so all return water from the house has to go thru the separator, just make sure it's sized for the flow rate, if the velocity is too high, or the separator too small, it will be less effective.
A minor change is I would have the air separator on the secondary after the boiler supply tee, it's easier to get the bubbles out of hot water.

Regarding the zone valves I assumed 2 zones not 12, maybe that's an option? You can zone with a 2 way valve in front of the manifold, you don't need to zone every circuit necessarily.

I agree with the others that a hydraulic separator with air, dirt, mag separation would be the nicest option, if you have purchased the parts yet.

Solid_Fuel_Man

My comment was zone valves, not actuators. One pump, two zone valves as there are two manifolds. But two circulators may give better results. @flyingmeatball

hot_rod

Use the combi discal/dirt/mag 5461. A 3in1 devicethat solves the location question

flyingmeatball

Interesting - hadn't considered zone valves. I appreciate all the helpful comments!

flyingmeatball

Ok here is the final:





The boiler is kicking out heat and all three circs are running. I let the system run for ~2 hours and the supply/return on the primary loop are getting hot (~110 according to the temp gauges), but the copper just beyond the zone circs is not all that warm - the temp gauges on the manifolds (not shown) are ~70 and a couple degrees colder on the return. The copper on the returns (above the purge valves) is also cool to the touch.

What gives? Is the lion's share of the water just going out the supply and in the return? Is something off, or am I just panicking? The circulators all felt hot to the touch, so I shut the system down - I didn't want to burn out a pump on day 1. Also, what should the pumps be set at (high/med/low?) Grundfos UPS-1558FC.

Thanks!

SuperJ

What's the temp delta on the boiler? And is the boiler using a system sensor, or just running on outlet temperature?
You probably want to set the pump speed so you get a 25-30degF delta on high fire with both zones calling. Sound like you should consider bumping the boiler pump speed up a knotch. I bet most of the flow is going across the closely tee's instead of the thru the boiler if the boiler pump speed is too low, or the system pumps are too high. You might be able to install a system sensor after the supply tee, the boiler would then run off that mixed temperature. That way if the flow is lower thru the boiler the system will still get water at setpoint.

If the boiler water is at 110-120f but the zones are at 70deg, you need to up the boiler/primary flow. If you have infloor in concrete it could take a couple days to come up to temperature, there is a lot of thermal mass in concrete especially if the slab is thick.

If the system is full of decent water and you aren't deadheading you won't wreck a pump. They should last 20-30years.

SuperJ

I would get a system sensor installed. Looks like you can handle a temp delta up to 40f, but the system sensor will be required if system flow is greater than boiler flow to keep system at setpoint. You want it that way so the boiler return temp is minimized to maximum condensation/efficiency.

You can use pressure drop or temp delta to confirm flow (I recommend checking both to be safe).

flyingmeatball

Thanks @SuperJ - it turned out to be a rookie mistake: I didn't bleed the air out of the loops properly. When I went one by one and bled the air out it started out fine. Now enjoying the nice toasty toes just in time for this record cold! -25 out today. It's taking a little tinkering to get the rooms to balance, one zone has engineered floating hardwood above the pex, the other is finished concrete.

SuperJ

Great I'm glad it worked out, thanks for sharing the ultimate solution.