Need Advise-Confirmation for Underfloor (Between Joist) Radiant Installation -Northern NJ-Zone 5

hcpatel78

Hello Everyone...I have been reading this blog for all information and be a great source of information here shared by industry professionals. I am a mechanical engineer who has decent hands-on experience with plumbing and understanding of the HVAC system. HVAC is not my primary field for my profession.....so I would like to take advice and learn from HVAC professionals for my little DIY project. I would appreciate of all your help and please correct me if I am doing something wrong with my lack of understanding and knowledge. I have been studying lots of articles, Technical books on HVAC rad design (JOHN S) and watch a series of videos by caleffi and some reputable companies to gather all information. Also, acquire a complex design manual from the UPONOR and study the whole manual.

I wanted to install (Supplemental Heat) radiant underfloor between the joist system. I Lived in Northern NJ (07828 ZIP) and keep design Delta T 70. We have a central air furnace for the house (60000BTU) for primary heating. House is built in 2007 with a 2x4 stud wall. Has R60 insulation on the attic and insulated basement walls with hybrid(2"Foam sheet R10 + R30 Roxul) walls. The basement is 30'x30' with the access of joist with 8' of ceiling ht. It's colonial two-story house. The radiant heat will be for the first floor which has 3/4" OAK hardwood installed on 23/32" thick plywood. I used a watts radiant software for my detail heat loss calculations, which came to 33000 BTUH for 70 delta T.
I have bought Noritz CB199-DV combi boiler for the heating source, it has 120K BTU heating capacity output. I have another tankless for DHW so I am going to use this new COMBI for only floor heating application.
I have put some basic diagrams together. Before I start to work on my setup, I would like professional feedback and OK for my design. Also, this is partially taken from the installation manual of Noritz combi boiler.
Please see the attached picture. Also please suggest any missing component in my design to make this as efficient & pleasing as possible

hcpatel78

Another challenge that how far I have to install Joist track plates from the joist hole where the tubing makes the turn in each joist.?

ScottSecor

I'm short on time right now so I'll be brief. It appears that your boiler is grossly over sized. As such I think it will short cycle and lead to a short lifespan. Is there any way you could return the boiler for a much smaller one? I'd hate to see you spend many hours installing this boiler, only to have it last a year or two and have to replace it.

Why a 120K btu boiler for a 33K load? We've all seen stereotype jokes about engineers overdoing things, this may be one of those cases. (lol)

GroundUp

The piping looks fine, but I have hard time believing you'll get anywhere near 33 BTU/sq ft output from that system with 1-1/2" of wood to transfer through at low enough water temps to not damage the hardwood. Also why on Earth did you buy a 199k combi to heat a 33k space and not use DHW? Seeing as it's only supplemental and your output will likely be closer to half that 33k anyway, the poor Noritz is not going to live a good life I'm afraid.

Ironman

As mentioned, the piping looks fine, but why a 199k btu boiler on a floor that can only output about 20k?

That particular boiler has also been plagued with 3 way valve issues.

hot_rod

Sounds like you have a 120K boiler for the load, not a 199? You could add a buffer and get that boiler to behave better if you do not want to switch it out. I think the 199 is only available for DHW?

Mid 20 BTU/ft is reasonable for residential systems running around an 80F surface temperature.

hcpatel78

ScottSecor said:

I'm short on time right now so I'll be brief. It appears that your boiler is grossly over sized. As such I think it will short cycle and lead to a short lifespan. Is there any way you could return the boiler for a much smaller one? I'd hate to see you spend many hours installing this boiler, only to have it last a year or two and have to replace it.

Why a 120K btu boiler for a 33K load? We've all seen stereotype jokes about engineers overdoing things, this may be one of those cases. (lol)

Hi ScottSecor... you are right about oversizing.... in that case I can't return boiler as I got a good deal on it and is almost paid up by rebates later on.
If it oversized then can I put some extra load by adding DWH loop.?
I have revisited the watts radiant software and recalculate the heat loss. Pls, see attached I want to understand the word in the report is in the red line.
Also attaching Boiler Spec. -Second Attachment

hcpatel78

hot_rod said:

Sounds like you have a 120K boiler for the load, not a 199? You could add a buffer and get that boiler to behave better if you do not want to switch it out. I think the 199 is only available for DHW?

Mid 20 BTU/ft is reasonable for residential systems running around an 80F surface temperature.

Hi Hot_Rod,
Thank you so much for your time and feedback
Yes you are right boiler part output is 120K with efficiency calculation it will be around 110K BTU output. I redid heat loss calculation pls. see attached . Could you please confirm that is it still ok to use this boiler for the given load?
I might be misunderstood my heat load in the first post which i mentioned....

hcpatel78

Ironman said:

As mentioned, the piping looks fine, but why a 199k btu boiler on a floor that can only output about 20k?

That particular boiler has also been plagued with 3-way valve issues.

Hi Ironman,
Thank you for confirming my design.
Do you think I need any other component like filter or dirt seperator in the whole hydronic design? I read multiple posts with 3-way valve thing with Noritz CBZ but it will be almost free after rebate that's the reason I chose this boiler.

hcpatel78

GroundUp said:

The piping looks fine, but I have hard time believing you'll get anywhere near 33 BTU/sq ft output from that system with 1-1/2" of wood to transfer through at low enough water temps to not damage the hardwood. Also why on Earth did you buy a 199k combi to heat a 33k space and not use DHW? Seeing as it's only supplemental and your output will likely be closer to half that 33k anyway, the poor Noritz is not going to live a good life I'm afraid.

Hi GroundUp , Thank you for feedback,
Yes, you are are right. After looking at my initial heat load calculations & after reading here lots of the post , I realized that it might be overkill...so redid heat loss calculation.....can you please look at again.?
I think initially i did some mistake to enter data in the watts radiant software ....

hot_rod

Maybe contact a local Watts rep or directly for help with the load calc. The results are related to the inputs, as you know.

Looks like that boiler input on heating is 18,000- 120,000 so if your load is 80K you are in the ball park.

Needs to be piped properly, I'd suggest a hydraulic separator for air, dirt, magnetic and hydraulic separation function.

GroundUp

What I'm not liking about your Watts paperwork is that the subfloor is at 3/4" but you have no floor covering listed. with another 3/4" of hardwood flooring, the subfloor should probably be doubled which is going to drastically reduce output. Also I see no mention of transfer plates in their design. That is going to be a huge variable as well. I just don't see any amount of transfer plates and insulation below with 6" spacing and 120 degree water being able to push 30 BTU/sq ft through 1-1/2" of wood Seeing as you already have this boiler, I think a buffer tank is going to be your friend. A regular old tank style water heater can even be used if you're working on the cheap. That will allow the boiler to run hard at full output (or less, if you like) and charge the tank to avoid short cycling of the boiler and increase life expectancy. Then the radiant could draw off that tank independently from the boiler on an as-needed basis. I would not try to use the Noritz for DHW, the 3 way valves are problem children but if you leave it always in space heating mode even if the 3 way fails it'll usually fail in the space heating position.

hot_rod

A Watts rubber tube staple up??

hcpatel78

> @GroundUp said:
> What I'm not liking about your Watts paperwork is that the subfloor is at 3/4" but you have no floor covering listed. with another 3/4" of hardwood flooring, the subfloor should probably be doubled which is going to drastically reduce output. Also I see no mention of transfer plates in their design. That is going to be a huge variable as well. I just don't see any amount of transfer plates and insulation below with 6" spacing and 120 degree water being able to push 30 BTU/sq ft through 1-1/2" of wood Seeing as you already have this boiler, I think a buffer tank is going to be your friend. A regular old tank style water heater can even be used if you're working on the cheap. That will allow the boiler to run hard at full output (or less, if you like) and charge the tank to avoid short cycling of the boiler and increase life expectancy. Then the radiant could draw off that tank independently from the boiler on an as-needed basis. I would not try to use the Noritz for DHW, the 3 way valves are problem children but if you leave it always in space heating mode even if the 3 way fails it'll usually fail in the space heating position.

Thank you ....the buffer tank idea would be great one...how about I add couple of baseboard for basement heat to the same boiler. Then I have to reconfigure whole piping as baseboard will run on different temperature. I was initially banking on the heat leakage from the joist that will take care of basement area. Basement is 30'x30' with 8' ht and fully insulated walls with R25.. what is your opinion on this idea?

GroundUp

There wouldn't be hardly any "leakage" downward from the joist if it was insulated like it should be. More leakage down means less output up, so pick your poison there. You'd likely need a lot more than a couple BB sections to heat a space that size, especially at the same temps as your staple-up. Maybe a radiant ceiling down there?

hcpatel78

ok any buffer tank brand you recommend? Should i keep the same capacity of buffer tank as the volume of the radiant system? I just check the smallest water heater tank i can buy is 19 and 30 gallons both the same price from box stores....

GroundUp

I don't have a buffer recommendation, sorry. I've only used them a few times and once with a Lochinvar 4 pipe but the others were just regular old electric water heater tanks. @Hotrod would be the man to talk to about buffers, he knows his stuff

hcpatel78

Thank you.... yes electric water heater tank would be the economical route. I have an old gas-fired water heater tank(75 gallons) but it is 13 years old so I don't trust that thing.

hot_rod

The buffer is often sized to assure a certain amount of time for the smallest load to run without cycling the boiler.

So two concerns, how long will the boiler run to charge the buffer, and how long of a boiler off cycle. We like to see the boiler have at least a 10 min run cycle every time it fires, this helps eliminate short cycling the components to an early demise.

Here is a common buffer sizing formula from this journal.

https://www.caleffi.com/sites/default/files/coll_attach_file/idronics_17_na.pdf

If you are considering using an electric water heater tank you may find that 40 gallon tanks are the least expensive. Size wise a 12 or 20 is often the correct size, but more $$ as they are less common.

hcpatel78

hot_rod said:

The buffer is often sized to assure a certain amount of time for the smallest load to run without cycling the boiler.

So two concerns, how long will the boiler run to charge the buffer, and how long of a boiler off cycle. We like to see the boiler have at least a 10 min run cycle every time it fires, this helps eliminate short cycling the components to an early demise.

Here is a common buffer sizing formula from this journal.

https://www.caleffi.com/sites/default/files/coll_attach_file/idronics_17_na.pdf

If you are considering using an electric water heater tank you may find that 40 gallon tanks are the least expensive. Size wise a 12 or 20 is often the correct size, but more $$ as they are less common.

Wow! that's great information. Thank you so much hot_rod.
Hiren

hcpatel78

The noritz CB199DV combi boiler has an inbuilt primary pump....if i hookup buffer tank then do I still need the extra pump for the primary loop (Boiler to buffer tank)? OR Will the inbuilt internal pump will be good enough for the purpose.? There will be a secondary circulator for the zone(From buffer to the supply manifold)

hot_rod

It can be this simple.

Here is the Noritz piping example, and the same function with a tank instead of the header they show.

Think of it as "super sizing" the low loss header shown in their drawing

hcpatel78

Thank you hot_rod.
I just updated my piping layout based on your suggestion. Please look attached...if anything missing...
I am still confused that my room Thermostat will turn on the secondary circulator based on heat call which will pull hot water from Buffertank+boiler......so do I need separate control for the boiler to turn on simultaneously?
OR
The boiler will turn on & off as soon as the flow detects by the secondary circulator?

hot_rod

The manual is vague on the ability to add a system sensor?

So on a heat call that relay box starts the zone circulator and also sends a signal to the boiler via the TT terminals, they show an example in the manual.

Ideally a sensor would go in or on the buffer tank so the boiler maintains the buffer. On a heat call flow goes from the buffer directly to the zone. When the tank temperature drops, that sensor tells the boiler to fire back up.

Anytime there is a heat call that TT terminal is closed, via your relay boxs. If the boiler is hot, obviously it doesn't need to fire, same with the tank, if it is warm enough the boiler will not fire.

In some cases I have moved the boiler control sensor from the boiler to the tank, basically you turn the boiler into a 40 gallon boiler.

On many brands they either supply that additional supply sensor, or offer it as an option. You might contact Noritz to see if they offer a sensor for this purpose. Maybe the manual better explains that, I didn't read the entire control section.

hcpatel78

Thank you hot rod. I will give a call to Noritz and see what kind of suggestion they have.

SuperTech

> @hot_rod said:
> The manual is vague on the ability to add a system sensor?
>
> So on a heat call that relay box starts the zone circulator and also sends a signal to the boiler via the TT terminals, they show an example in the manual.
>
> Ideally a sensor would go in or on the buffer tank so the boiler maintains the buffer. On a heat call flow goes from the buffer directly to the zone. When the tank temperature drops, that sensor tells the boiler to fire back up.
>
> Anytime there is a heat call that TT terminal is closed, via your relay boxs. If the boiler is hot, obviously it doesn't need to fire, same with the tank, if it is warm enough the boiler will not fire.
>
> In some cases I have moved the boiler control sensor from the boiler to the tank, basically you turn the boiler into a 40 gallon boiler.
>
> On many brands they either supply that additional supply sensor, or offer it as an option. You might contact Noritz to see if they offer a sensor for this purpose. Maybe the manual better explains that, I didn't read the entire control section.

What would be the difference in operation from controlling the boiler from an aquastat on the buffer tank as opposed to leaving the aquastat on the boiler and trying to control the temperature of the tank there? Would the tank not perform correctly?

hot_rod

SuperTech said:

> @hot_rod said:

> The manual is vague on the ability to add a system sensor?

>

> So on a heat call that relay box starts the zone circulator and also sends a signal to the boiler via the TT terminals, they show an example in the manual.

>

> Ideally a sensor would go in or on the buffer tank so the boiler maintains the buffer. On a heat call flow goes from the buffer directly to the zone. When the tank temperature drops, that sensor tells the boiler to fire back up.

>

> Anytime there is a heat call that TT terminal is closed, via your relay boxs. If the boiler is hot, obviously it doesn't need to fire, same with the tank, if it is warm enough the boiler will not fire.

>

> In some cases I have moved the boiler control sensor from the boiler to the tank, basically you turn the boiler into a 40 gallon boiler.

>

> On many brands they either supply that additional supply sensor, or offer it as an option. You might contact Noritz to see if they offer a sensor for this purpose. Maybe the manual better explains that, I didn't read the entire control section.



What would be the difference in operation from controlling the boiler from an aquastat on the buffer tank as opposed to leaving the aquastat on the boiler and trying to control the temperature of the tank there? Would the tank not perform correctly?

Sure, the boiler sensor is basically a connection to an onboard aquastat.

I think the onboard control may have more functions and adjustability compared to a basic aquastat.

An electronic set point control may be better, more adjustability.

I think Lochinvar includes the supply sensor, my Nobel came with one, no need to buy another control.

hcpatel78

Hi,
I am going to buy caleffi manifold
https://www.supplyhouse.com/Caleffi-6686D5S1A-1-TwistFlow-Manifold-4-Outlets .
My all tubes dropping from the ceiling. So can I convert myself this manifold as "Inverted"? Or Do I have to buy little expensive inverted version ?

hcpatel78

I can't find any video or instructions to convert in inverted.

BillyO

it definitely can be done in the field

hcpatel78

> @BillyO said:
> it definitely can be done in the field
Thank you. Supply house was nice to match the price of the inverted manifold same as regular Caleffi S1 manifold.

BillyO

Great, I order inverted all the time for no extra charge from Don Rathe. But I have done in the field twice . Glad it worked out

hcpatel78

I am starting to hook up a connection with the boiler now. I have a question regarding the boiler manifold kit which I bought with the boiler. I am piping this boiler with a buffer tank(40-gallon electric water heater tank without power). Should I use this Norits preassembled manifold Kit( MK_CB_1) which creates P/S loop?
Please see attached pics.

hcpatel78

Any expert opinion?

SuperTech

I don't think you would need the preassemled manifold kit with your design. The buffer tank will do the same job as the low loss header.

hot_rod

Just fine as your drawing shows, no need for the additional manifold.

hcpatel78

Thank you "Super Tech" & "hot_rod".

hcpatel78

Hello All, I bought the 30-gallon lowboy electric water heater to use as a buffer tank. I wanted to use 1 1/4" fittings at the inlet and outlet of the buffer tank. I will go with 2 pipe configuration. My biggest challenge is what kind of fitting needs to be used. I am leaning toward to convert 3/4" (hot& cold) side port and upgrade to 1 1/4" for short length and then switch to 1" piping towards manifold and boiler. Am I doing it correctly. Need to find out the fittings and source.
Please see the attached picture.

hot_rod

Here are some options. A 3/4 male X 1-1/4" copper adapter.
A 1-1/4 X 3/4 reducing coupling, shown is a 1-1/2" in stainless.
Or a 3/4 x 1-1/4 bushing with a regular 1-1/4 ell.
Depends on the use of copper or threaded pipe?

hcpatel78

Thank you Bob 

hcpatel78

 
Can I apply wrench on 1-1/4" copper pipe to tighten the thread on 3/4 threaded coupling at the tank end?