New 3 floor NCB-240 Setup Using 3/4" zone valves.

cybersurfr

Hello All,

Multi year/decade lurker here, mainly for the helpful repair stuff. We built a home this year, and put in a NCB-240 as well as staple up Joist PEX for radiant heating. We have lived in the place for a year using the 90K furnace quite fine, but I am now looking into completing the system for comfort purposes. I was hoping to get a sanity check/ suggestion from other on my plan...

Currently the boiler only has its primary loop in 1"



We have 3 floors ideally we'd like to heat:

Basement: In slab 900 sq ft : 6 loops manifold (5 around 220, 1 super short at like 100)

Basement GPM : 3GPM @ 20 Delta T

Main floor 4-5ft head: 1100 sq ft : 5 loop manifold around 200ft

Main Floor GPM: 2GPM @ 20 Delta T

Upper floor 1200 sq ft, 15ft head.: w/remote manifold 6 loops around 250ft this is serviced by 3/4" lines.

Upper Floor : 3.2GPM @ 20 Delta T

Heat loss: 80,000 BTU @ -25C or -13F - We have R32 walls, and R60 ceiling. and continuous foam insulation on the outside to eliminate thermal breaks.

We have vinyl flooring so water temp will stay low, to keep floor 80-85F


The NCB has built in control to control 3 zones, so as I am trying to find the most cost effective approach, which seems to be doing 1 zone per floor in order to enable using the built in control on the Navien. from what I have read with my max heat loss where it is , I should be able to use 3/4" Zone valves, or 3 pumps as 3/4 pipe can carry those BTU's.

My plan:


1. is to use a single Grundfos ALPHA2 15-55 or equivalent adaptive style pump
2. 3 Honeywell Zone valves at 3/4" this one here
by placing the zone valves on the return line to each manifold.
3.Each manifold will be serviced by a 3/4" supply and return.


I am hoping this is a reasonable plan, it seems there is many, many ways to do this , but this is the most cost effective I could come up in my area. being from Canada we can't access pex Supply, or supplyhouse as they do not ship to us, so we have a much smaller pool of places to purchase from at reasonable cost. I know 99% of people do this in copper , and I absolutely can sweat pipe, but I was planning to do it in PEX for costs sake again.

Welcome all your thoughts.

EdTheHeaterMan

This is what the manual has for the 3 zone connection using zone valves (with some minor changes for your situation). The pipe sizes I am suggesting will work for 80,000 BTUh Net heat loss based on a 20°F ∆T. Radiant floor heating is normally a 10° to 12° ∆T design so the pipe sizes may need to be increased. And usually PEX tubing has a slightly smaller inside diameter than copper tubing. so you may need to use 1" PEX with 1-1/4" PEX for the shared piping. Even though the fitting sizes and the boiler connections are 3/4" and 1" you still need to consider the temperature change from supply to return (∆T) and the actual gallon per minute flow needed to move 80,000 BTUh as the lower ∆T.

Sorry for the Fahrenheit # but it is what I'm used to and I don't feel like converting this late at night.

Changing from a 1-1/4" that is 20 ft long to a 1" fitting for a foot or so, then back up to 1-1/4" for the remainder of the shared piping will only create a small amount of restriction but the design will most likely work. Having the entire shared piping manifold all 1" may be a problem. Likewise having a 1" PEX pipe reduce to a 3/4" zone valve and then back up to 1" PEX will have little affect on the design, but having the entire branch piping from the shared piping to the loops back to the shared piping, can be a major restriction causing the system have less capacity. (you can't fit 10 pounds of potatos into a 5 pound sack!)

So to be sure of the pipe/tubing sizes, you will need to provide the BTUh needed for each zone in order to determine if 3/4" is enough or not. Do you have the Gallon Per Minute numbers needed for each loop of tubing on each manifold/zone? With that info, there is a way to calculate the necessary tubing sizes.

To be entirely safe you can look at the attached file for the tubing size you may require to make the system operate when it gets really cold.

cybersurfr

Man oh man , having a second set of eyes is helpful . It did not even cross my mind to reduce to 3/4 for the zone valve only. Then simply go back to 1”. Two of my manifolds are in the boiler room, so easy enough to do that for those two, but that does also make me wonder if the 3/4” would effectively matter at those distances? I can do either but It is likely no more than 3-5ft from the boiler to those two manifolds . 

The remote manifold on the upper story, unfortunately was pulled with 3/4” by someone else and it is sealed up so there is no changing that now. 

Thanks so much for this , I’m going to try to find the GPM tomorrow and update .  

hot_rod

80K load, what size is this new home?

cybersurfr

The home is 3300 ”livable” sq ft includes the basement. The load is based on -25C (-13F). 

cybersurfr

@EdTheHeaterMan I updated the post with the GPM per floor. Only issue is, it was done at 20 Delta T. Not sure how to compensate for a lower delta

hot_rod

That load number seems high to me? Well insulated homes like yours are seeing numbers in the teens. BTU/ sq ft. You are in the mid 20 btu/ sq ft.

I like hydraulic separators as you get all the crucial pieces in one 'box". Air sep, dirt sep and the ever important mag sep that all ECMs circs need to have.

Here is a friends 3300 sq. ft. home in a -5° design upstate NY. 10 btu/ sq. ft load.

cybersurfr

I do live in an Exceptionally cold part of Canada, if that matters. These temps, and likely worse will be seen 2-4 weeks of the year. We do see a week or two of -35C or -31F per year. So this design, while hopefully capable of that, will rarely see it.

There was also a considerable amount of window loss, as the place has more windows that I would even like. The surface area of window accounted for nearly 50% of the heat loss at -25C

That being said, I do have a Nat gas furnace also, so I am not entirely worried about actually going cold, Just want to do it as best as possible , and call it done.

hot_rod

The heat load is  all about the structure and build quality 

Oversizing a little with a mod con is not a dealbreaker 

pipe and component costs jump when you go to 1-1/4, if 1” could meet the load

Also I feel there is a 10% fudge in the heat loss formulas 

Even more when an aftermarket load calc is based on manual J and another CYA factor is added

cybersurfr

So, I completely forgot my Thermostat for my furnace keeps its performance data. So I was able to check on the thermostat for the regular furnace for the coldest day last year, which was about -28C.

Looks like during that 24hr period my 90K furnace ran for 6.5hrs on LOW Fire, and 1.5hrs on HIGH fire. For a total BTU output of 494587 over a 24hr period. and maintained 22C in the house. (72F for my American friends)

My simple mind seems to think that averages to 20K/hour and if I divide that by the sq footage of the building it is only 6 BTU/ sq ft.

@hot_rod seemed to indicate the other calculations seemed high, and based on this perf data , I am inclined to agree.

I am not sure how this affects pipe sizing though, if at all. but again, my simple mind seems to think with all the extra insulation we did, we only need 20K BTU/hr to keep this place toasty. and so , ANY pipe should work as they all can carry more than enough BTU : 3/4 PEX or 1" PEX, or 1" copper. I can do any , but as you mentioned the costs jump significantly at larger pipe sizes, so trying not to unnecessarily waste $$

hot_rod

1” copper  piping at the boiler, 3/4 or 1” pex to the manifolds
Depending on the distance and number of loops on the manifolds

Its good to have some actual data to check the calcs

EdTheHeaterMan

I thought your home was much larger when you posted 80,000 BTUh. Agree with @hot_rod, Your Load Calculation is incorrect on the high side by a lot. The diagram that I doctored up came from the I/O manual for that boiler.
I believe you may be able to use the smaller boiler NBC-190 unless you are looking for the Domestic Hot Water (DHW) capacity of the 240.

That said, you are probably OK with 3/4" branch to the zones and 1" for the shared piping, since your actual usage is about 1/2 of what was calculated. That is evident by the fact that your 90,000 input furnace only needed 8 hours of run time (most of that on low fire) in a 24 hour period. If you had a 40,000 BTU furnace that ran for 18 hours, you would get the same amount of heat. But that math is flawed because it does not show the time the furnace operated during the coldest portion. of the day (overnight when the temperature reached -28°C). If the furnace operated on high, for the full hour when the outdoor temp was at its coldest, and then the temperature rose up to 8°C that day, then the furnace would have needed the full capacity to keep the home comfortable when it was cold. and the home didn't need that much heat when the temperature increased drastically that afternoon.

That probably didn't happen but stranger things have happened in New Jersey. My guess is that your 6 BTU/SqFt is really low, and your 80,000 is probably almost double. So being that your boiler will modulate the output as needed, and you have a choice of 110,000 BTU for the space heating side of the boiler you will never be able to use the full capacity of the boiler with 1" and 3/4" piping sizes. Knowing that, if you reach the extreme temperatures of -35°C and the system does not keep up, the following summer you can decide if you want to increase the tubing sizes or just use the furnace as a backup.

cybersurfr

Thanks again @EdTheHeaterMan so much helpful info. I took a look at the performance data again, and the overnight 9.5 hours was a solid -25C to -28C ( around-13F) . when I looked at the run time specifically for those hours ONLY. I came out with the following:

The furnace ran : 3.26 hours on LOW fire , and 1.05hrs at high fire. The math worked out to 275,000 BTU's for those 9.5 hours

So at those temps and run times that seemed to yield a more moderate 28,947 BTU/h , and when divided by the sq footage a more modest 9 BTU/sq ft. so, I feel like aiming for "low teens" BTU sq ft. Is prob the right call here?

I already have had the NCB-240 installed for over a year with only a primary loop, so the boiler decision is a done deal, and you are right, we got that size for the DHW. I was looking in to this solely to decide if I could use 1" pipe and get the BTU's necessary.

I shall wait for you to blow another hole in my logic in short order

EdTheHeaterMan

LOL. Not trying to blow holes, Just trying to help. Here is the scenario to understand how heating systems work.

With a simple on off thermostat and only one stage. the 90,000 BTU furnace will only run at 90,000 or off. So, if your home needs to replace 9000 BTUs in any given hour, it will run for 6 minutes and be off for 54 minutes. That might happen when the outdoor temperature is 18°C. When the temperature drops to 0°C your home may need 30,000 BTU in a given hour. That means the burner will run for 20 minutes in that hour. But it may only operate for 6 minutes on and 12 minutes off several times. Now when you get closer to -30°C the off time will be longer and the on time will be shorter. The goal is to get the input of the heating appliance to be as close as possible to the actual need. that is because turning on then off is wasteful. The heater doesn't not reach its steady state efficiency until it operates for 5 minutes or so.

Following that logic, if the burner operates for 6 minutes and shuts off, then it was only at its peak efficiency for 1 minute of the run time. The other 5 minutes... it was less efficient, on its way to peak efficiency. If we size the appliance as close to the needed design load, then the burner will not shut off for the entire time it is that cold out. If you have a burner that can heat a building twice the size as you need, Then on the coldest days (or nights) the burner will only operate 50% of the time. It will not be 30 minutes on and 30 minutes off. it will be more like 7 minutes on and 7 minutes off for as long as the temperature outside is that cold.

When the outdoor temp rises then the burner will operate 7 minutes on and 10 minutes off. As the temperature outside rises more the cycle might be 6 minutes on and 12 minutes off, and so on... So having a heater that is too big is inefficient.

Since you already have the modulating boiler, is it the 240/110 or the 240/130? You only need the 110 but if you have the 130, not a problem. Either way, the burner in that boiler will only operate at the capacity needed to maintain the indoor temperature. If you only need 45,000 BTUh on the coldest nights, then it will only ramp up to 45,000 BTUh. You will never be operating a space heating boiler at the full 110,000 or 130,000 because the thermostat and sensors in the boiler will never call for that to happen. But it's good to know it is there if you ever need it. (the mother-in-law apartment addition)

EdTheHeaterMan

As far as the pipe sizes, I would go with the 1" PEX and copper for the shared piping and use the 3/4" PEX to the zones.

As far as the math for determining the different GPM for different ∆T. if you need 3 GPM for a 20° ∆T then you need 6 GPM for a 10° ∆T to provide the same amount of heat transfer. from point A to point B. But that may not work out actually without changing the heat emitter design... and you are not going to redesign the floor plan of the house to add more tubing. You need to work with what you have installed and believe that the design will produce the needed result. When it was planned out, the GPM thru each radiant loop added up to the total GPM for the zone manifold. There are tweaks that can be made to get better performance from the system. And rest assured that what you have is better than nothing at all.

cybersurfr

hoping i can ping @EdTheHeaterMan once more… I got most things together but I ended up with two questions

1. In an all plastic staple up  system like mine , with an ECM pump, is a magnetic filter really necessary ? 

2. I was planning to put 3/4” sweat zone valves to each manifold. I found a really good deal on 3/8 Honeywell zone valves though , that come with 3/8 flare to 3/4 sweat ons , would I be shooting myself in the foot by using the 3/8? 

It is the Honeywell V8043C5033 . If I am better off staying 100% in 3/4 , I don’t want to “sacrifice” anything to save a bit of money , but if it’s all the same , I’d also rather not overspend  thoughts ? 

hot_rod

Yes to the mag sep. The pump and expansion tank is ferrous metal, maybe some piping.

The thing to know about zone valves is the Cv number. You could get by with a Cv as low as 3 and be fine.

Cv = gpm thru the valve with a 1 psi drop. You may be flowing 2- 4 gpm in 3/4 baseboard, so within the range ofa 3 Cv valve.

It sounds like you are looking at inverted flare valves. Very common in the midwest still for the easy removal and serviceability.

cybersurfr

Thanks @hot_rod , what’s in the picture is very very similar to what I’m looking at. I can also get the 3/4” sweat which has a CV of almost 8 , but correct me if I’m wrong this is not “better” just wasted flow rate I don’t need ? That’s the way I’m thinking , but I’m curious if it’s the correct thought process.

EdTheHeaterMan

I just got your ping. But I will pong it to @hot_rod. He is the man with all the books on Cv. Personally I'm a Cd kind of guy. Although I do have a decent vinyl collection too. I might even have a few old cassette tapes in a box in the basement. I keep them with my floppy disk collection.

hot_rod

cybersurfr said:

Thanks @hot_rod , what’s in the picture is very very similar to what I’m looking at. I can also get the 3/4” sweat which has a CV of almost 8 , but correct me if I’m wrong this is not “better” just wasted flow rate I don’t need ? That’s the way I’m thinking , but I’m curious if it’s the correct thought process.

This type of zone valve is just an on / off control valve. If it were a control valve, like a balance valve, then Cv plays more of a part to assure what is called "valve authority"

At the flow rates I think you have, up to 4 gpm? any valve 3 Cv or more would work.

Here is what a 1 and a 3 Cv valve would look like with a 4 gpm flow. A 1 Cv valve with 4 gpm flowing cost you 36' of head!! probably not a good option in your system

A 1 Cv valve gets used in systems that need high close off pressure, up to 75 psi.
Higher Cv valves 7- 8 Cv are usually 10- 20 psi shut off. Plenty for residential work.

Bottom line, confirm the Cv of the valves you are considering.