Primary / Secondary doesn't work

Richard Miller

25K to 194K input

because of head pressure numbers for floor. all one zone. 44' X 84' building. reformatted computer and lost heat loss number because I forgot to back them up.

no, he says pumps are as drawn. am on the phone with him at the moment. he is living in 2 places for a month or so more. he is on the way to Tunas at the moment. I told him to get some actual pics on the way before he gets into town.

Richard Miller

Primary / Secondary doesn't work

OK, I know it does. But I am trying to diagnose a problem with such a set up.

Richard Miller

Primary / Secondary doesn't work

OK, I know it does. But I am trying to diagnose a problem with such a set up.

Richard Miller

Primary / Secondary doesn't work...

OK, I know it does. But I am trying to diagnose a problem with such a set up. It doesn't make it any easier that the job is 1,100 miles from me.

They already had the tubing in, the Noritz purchased, and the B&G circ purchased when I got involved. My kid brother is starting out and I am trying to help him get started right. He is 60 miles north of Springfield, MO.

OK, I did a heatloss to check their tubing. All is well. Got the head for the systm and it required a Taco 0011 so I got one for them. I checked the requirements for the Noritz and found I needed 1.58 GPM at 10' of head. According to B&G the NRF-22 is more than adequate for this.

I did not draw in the relief valve, guages, etc. that are before the air eliminator.

After the B&G pump there is the 90 to the left. There is 8" between the 90 and the first tee. The tees are just under 4" apart (center to center). Then it is 8" before it turns vertical into the WH.

The tees for the secondary point straight out from the wall and then 90 down.

I am enclosing a hastily scribbled diagram of how he piped it. But it's not working right.

Reported problem: It is hot coming out of the WH right to the first going out to the radiant floor. At that tee it turns relatively cool. If he chokes down the ball valve on the secondary return enough it will go ahead and turn hot in the secondary supply.

I had him check the filter in the Noritz. 30% clogged so he cleaned it. Only difference now is that he doesn't have to choke the secondary return quite as much.

It seems like, from what I can understand, that the 0011 is overcoming the B&G and in doing a reverse flow between the two tees.

The WH does not run much but as soon as they choke down the secondary return the WH kicks on.

I am kinda rusty after being out of it mostly for the last 2 years. Can anyone help me and my kid brother out with this?

Thanks.

Richard

PS. This job is for his church's new building so a LOT is riding on it. Already has some claiming that radiant is just a fad and they ever should have used it, yada, yada, yada. So if we can get this resolved it will go a long ways to him having credibility as he starts up his business.

PPS. I miss the old wild and wooly days on www.danholohan.com. Yeah, some bad things happened. But we had a ball didn't we?

Richard Miller

Primary / Secondary doesn't work...

OK, I know it does. But I am trying to diagnose a problem with such a set up. It doesn't make it any easier that the job is 1,100 miles from me.

They already had the tubing in, the Noritz purchased, and the B&G circ purchased when I got involved. My kid brother is starting out and I am trying to help him get started right. He is 60 miles north of Springfield, MO.

OK, I did a heatloss to check their tubing. All is well. Got the head for the systm and it required a Taco 0011 so I got one for them. I checked the requirements for the Noritz and found I needed 1.58 GPM at 10' of head. According to B&G the NRF-22 is more than adequate for this.

I did not draw in the relief valve, guages, etc. that are before the air eliminator.

After the B&G pump there is the 90 to the left. There is 8" between the 90 and the first tee. The tees are just under 4" apart (center to center). Then it is 8" before it turns vertical into the WH.

The tees for the secondary point straight out from the wall and then 90 down.

I am enclosing a hastily scribbled diagram of how he piped it. But it's not working right.

Reported problem: It is hot coming out of the WH right to the first going out to the radiant floor. At that tee it turns relatively cool. If he chokes down the ball valve on the secondary return enough it will go ahead and turn hot in the secondary supply.

I had him check the filter in the Noritz. 30% clogged so he cleaned it. Only difference now is that he doesn't have to choke the secondary return quite as much.

It seems like, from what I can understand, that the 0011 is overcoming the B&G and in doing a reverse flow between the two tees.

The WH does not run much but as soon as they choke down the secondary return the WH kicks on.

I am kinda rusty after being out of it mostly for the last 2 years. Can anyone help me and my kid brother out with this?

Thanks.

Richard

PS. This job is for his church's new building so a LOT is riding on it. Already has some claiming that radiant is just a fad and they ever should have used it, yada, yada, yada. So if we can get this resolved it will go a long ways to him having credibility as he starts up his business.

PPS. I miss the old wild and wooly days on www.danholohan.com. Yeah, some bad things happened. But we had a ball didn't we?

Richard Miller

anyone?

hr

1.58 GPM ?

what size heater (BTU) is that. Also why a 0011 on the secondary? Seems the boiler side and the distribution side is out of wack?

I've not had much luck with instantanous WH's. Most NEED a high head circ to get much of any output. Are you sure your circs are not swaped?

hot rod

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

brucewo1b

I agree with Hot Rod Check application links below

http://fhaspapp.ittind.com/homeowners/NRF-Typical-Application.asp

http://www.taco-hvac.com/en/products.html?view=ProdDetail&current_category=52&Product=13

Richard Miller

The 1.58 GPM number comes from the Noritz installation manual on the diagrams for using it for hydronic heating. Seems pretty low to me.

It is a sweet lesson to my kid brother why I tend to shy away from using instant WHs for heating.

Richard Miller

Thanks for the links. But so far I don't see any issues. Unless I am missing something.

I am wondering about the B&G pump being adequate.

Richard Miller

He is in Buffalo (means something to HotRod) right now. I thought he was 2 hours away yet. So I will have my first pic in 20 minutes or so.

Boilerpro_3

I don't see the problem

If the heater loop is flowing 1.58 gpm and the floor loop is alot higher flow, most of the floor return water will flow back to the supply and mix with the hot water coming out of the heater. The flow between the tees in P/S can go either way,reverse flow is not a problem and is quite normal in most of my installs. That is one of the beauties of the pipng arrangement, you dont need to sorry about the flow rates. You didn't say what the floor flowrate is but, I bet it is alot higher than 1.58 GPM. The only way the floor supply is going to get to the same temp as the heater supply is if it is only flowing 1.58 gpm or less.

Sounds to me like everything is working just fine.

Boilerpro

Richard Miller

Interesting. What is making this harder for me is the fact that I am not much more than a zombie the last 3 days due to being ill. I can barely focus my thoughts, let alone diagnose something 1,100 miles away.

Thanks guys. Anyone else have any input?

Rock2

Maybe you may have an air problem.

hvacsale

Some additional info please....

You didn't mention what the design temp of your radiant system is and also the current operating temperature of the Noritz.

A 0011 for the radiant may or may not be a large pump, how many loops of what size tubing and length is your system? What is your design head loss on the radiant side?

1.58 GPM through the Noritz would require a huge delta T in order to deliver 194k. Allowing for only 80% (194k input X .80 = 155.2 mbh) efficiency you would need better than a 196 degree delta tee at 1.58 gpm in order to get the full usage out of the Noritz.

This leads to the next question: What is your heatloss on the building? In order to calculate the minimum flow of your primary, we need the delta T between the Noritz unit supply and the radiant return temperature.

Richard Miller

I forget the specs on the building but if I remember right we were at about 75K head load.

They had the tubing in, the Noritz hung and were going to use the B&G for everything.

I really need to tell him to shelve it for the night as I my eyes are crossing on me and stuff. Am on some meds and can barely function.

I think I will just do a new heatloss on it in the morning if I feel good enough.

Alex Giacomuzzi

I Agree.......

I agree with what Steve has concluded above.
The 1.58 gpm would work for the 25K Btuh input , but it certainly will not work at the top end. There is something very wrong with the flow rate thru the Noritz.
Without referencing their literature, I would assume you should have something around 10 gpm which puts you into the 30 delta T camp.

The other thing to remember is..... and I presume you are heating a concrete slab..., that junction point temperature that you talk about being cool, given the flow rates that you are describing and a huge cold concrete mass out there..... you have it. It will be cold for a good long period of time until the slab starts to heat up. The higher flow pump is circulating a (presuumed) higher flow rate versus the 1.58 flow and the mix temp is still cold.

What are the pipe sizes into and out of the Noritz? Can you flow 10 gpm comfortably? Just some thoughts to soak on......

Regards Alex

hr

Is that a condensing boiler?Hooked to a radiant slab, without re

> I agree with what Steve has concluded above. The

> 1.58 gpm would work for the 25K Btuh input , but

> it certainly will not work at the top end. There

> is something very wrong with the flow rate thru

> the Noritz. Without referencing their

> literature, I would assume you should have

> something around 10 gpm which puts you into the

> 30 delta T camp.

>

> The other thing to remember

> is..... and I presume you are heating a concrete

> slab..., that junction point temperature that

> you talk about being cool, given the flow rates

> that you are describing and a huge cold concrete

> mass out there..... you have it. It will be cold

> for a good long period of time until the slab

> starts to heat up. The higher flow pump is

> circulating a (presuumed) higher flow rate versus

> the 1.58 flow and the mix temp is still cold.

> What are the pipe sizes into and out of the

> Noritz? Can you flow 10 gpm comfortably? Just

> some thoughts to soak on......

>

> Regards Alex





To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

hr

Is that a condensing boiler?

Because connected to a radiant slab, without return protection, it will see some long run times below 130.

Does the manufacture approve that unit for radiant applications?

Some of those instantanous do not modulate properly in an application like that.

Plenty of Munchkin dealers, with inventory not too far from that job

I don't see aproblem with the piping as shown, but I still question the 1.58, even with a 75 K load. Looks like a 90 degree delta t?

hot rod

Richard Miller

Gotcha on the munchkin dealer nearby!

I was in a brain funk the last few days like i said. Today I am much clearer but can't reach my brother.

Yes, this unit is approved for radiant.

The 1.58 was the number Noritz gave and in my fog I accepted it. Stupid me. Today it is so clear to me that something is really wrong with that number. Tucking tail and slinking out of here in embarassment. LOL

Man I was brain fried wasn't I?

I just got the pics this afternoon.

I'll let ya'll know what turns up.

hvacsale

re: radiant and Noritz

Being a water heater, the Noritz shouldn't have any issue with low return water temperature since it is meant for input water in the 45-50 degree range.

That being said the pressure drop in the Noritz, like all instantaneous water heaters, is based around incoming city water pressure which is easily in the 50-75 psi range. A residential sized circulator with a pressure change of only a few pounds is going to have it's work cut out for it trying to move water through.

It seems likely that your primary pump will need to increase in size to deliver the necessary flow. I used a Noritz on a job (at the customer's insistance NOT mine) and had to use a 0013 to insure proper flow in the primary loop. The delta T in that job had to be much tighter than what you should be able to maintain in this application but don't be surprised if a 0010 or equivalent is needed.