I guess there’s a reason why plumbers can charge so much...

Gordy

I think the 100k ch rating is miss leading. Based on?

hot_rod

Gordy said:

I think the 100k ch rating is miss leading. Based on?

Wishful thinking on the manufacturers part. Tankless turned boiler?

It should be capable of 45,000 btu/hr, which may still be shy of his actual load regardless of the undersized fin tube?

Or time to make the house's heat load fit the boilers ability.

Gordy

Is this the CB 180?

If so

Ironman

One thing that's not readily understood about combi boilers is this: just because the burner can produce 199k btus doesn't mean that much heat can be delivered to the emitters.
The onboard circulator is rated for about 4.5-5.5 gpm. It's sized for the domestic plate heat exchanger, which at that gpm and a 77* temp rise (delta T) through it, will give about 5 gpm domestic hot water.
The problem lies on the space heating side: at 5 gpm, you're only gonna get about 50k btus delivered to the house for space heating .Btus = (gpmx500) x Delta T.
High temp BBs are generally sized for 180* SWT and a 20* delta Tee. At 5 gpm, that translates to 50k btus.
Think of it this way: at train is is being loaded at the station (the boiler). The station has 199 tons of cargo (btus) to be delivered, but the train (the circulator and piping) can only carry 50 tons of cargo at a time to the depot (the emitters).
Unless you oversize your BBs so that they can operate at a lower SWT which would allow for a wider delta T, you're not gonna be able to get enough btus to them.

Gordy

I’m not sure how to interpret the two charts in correlation to pressure drop of the HX.

Gordy

So does the previous one in my other post give the pressure drop with the HX included?

I think this one is for DHW flow rate🤷‍♂️

Your stuck with the primary pump, and flow rate. A larger pump may have undesirable results, and of course I doubt noritz would approve.........

Ironman

@Gordy
I think the second chart is DHW production.

Ironman

@CoryH
The Universal Hydronics Formula: BTUs = (gpm x 500) x Delta T.

Most U.S. hydronic systems are sized for a 20* Delta T. This simply translates to 10k btus for every gpm. With a 4.5 gpm onboard pump, you're only gonna get 45k btus delivered to the system and its emitters if they are looking for the 180* maximum SWT that the boiler can supply.

Basic physics: Heat moves toward cold. The greater the temperature difference (Delta T), the faster it moves. If you over-size your emitters (as I stated earlier) to where you could utilize a 140* SWT, then the Delta T between what the boiler could supply (180*) and what the emitters required (140*) would be 40*. With that Delta T (40*), at 4.5 gpm, you would get 90k btus delivered to the system and emitters.

Please carefully review your heat loss calc and the construction data that you entered into it so we can know what the actual heat loss of the house and what target to shoot for. The heat loss calc is THE FOUNDATION for sizing and designing EVERYTHING in a heating system and should always be the first step before anything else is done.

Gordy

Yes @Ironman the only real solution is as you say getting the emitters to play with a lower AWT.

If the house is a cold start, meaning no supplemental heat while work is in progress. Or very low set point. You must be patient reaching a reasonable ch set point. Also doing a setback program once up to temp not recommended.

CoryH

How do I come up with the numbers you all are talking about? I’m obviously in way over my head

hot_rod

Run your heat load calc again, most everything we are discussing really revolves around what your home actually needs for heat input.
My gut tells me you can massage what you have to cover the load, boiler wise, additional baseboard would be ideal, maybe necessary once you have an accurate load number.

This one is user friendly some tutorials available if you get stuck.

https://www.slantfin.com/products/virtual-heat-loss-calculator/

CoryH

@Ironman , when you say “oversize the emitters” can you explain why you mean by that please. And what is SWT?

hot_rod

CoryH said:

How do I come up with the numbers you all are talking about? I’m obviously in way over my head

go to the SlantFin website for access to a free heat load calc, they have tutorials to help you through. Use the version at their website. I had a link attached but it will not post without"approval"?

We all need to know that load number, I suspect you are short, the load number will tell.

Ironman

CoryH said:

@Ironman , when you say “oversize the emitters” can you explain why you mean by that please. And what is SWT?

Increase the size of the BBs to where they can give off enough heat with 140* Supply Water Temperature (SWT). This is where I said to use the 380 btus per lineal foot number. At 140* SWT, most BBs will emitt about 380 btus per lineal foot.

If you had a room that had a heat loss of 5k btus: 5000/380 = 13.1 feet of BB. round it up to 14 feet.

Gordy

I believe he used it. @hot_rod . @CoryH you need to take the time to get the inputs in the program correct. It’s not a 10 minute event.

Over sizing emitters allows a lower average water temperature.

hot_rod

Not to overwhelm you with info... When heat emitters are in series, each section down the line sees a lower SWT, Supply Water Temperature so the output will decrease. Here is a simulation program I use to determine sizing. Notice what happens to the 180 SWT supply water temperature as it passes along. So the 550/ ft output the fin tube chart might show per foot is a bit deceiving.

Another option is to use high output in areas that are undersized, either a taller fin or a double stack of fin basically.

If you want to run lower temperatures here is an example of how you can beef up output with additional panel rads.

Also a home run piping method is nice as each row of fin tube gets the same SWT, so output doesn't drop as when put in series.

You mentioned combining 5 zones into 2, that may give you the series drop condition, last fin tube on the line will have a lower output.

Caleffi Idronics 25 was a look at taking old legacy high temperature systems and modifying to run lower SWT.

SuperJ

You mentioned the boiler doesn't run consistently. You can play with the on /off differentials. You don't want short cycling (would target 10min or longer cycles). But a 30degF start offset is pretty big. Try winding it down a bit, so it will kick on sooner.

SuperJ

Your boiler appears to have some sort of autofeeder control for makeup heating water. You've got two makeup water feeds. You don't need the second one by your dirt separator because your boiler is filling itself internally to a default of 12psi.

If the boiler see 4psi less than setpoint it will shut off.

Since it's using a pressure sensor to control this, it's important your expansion tank is correctly locating in the system so that you don't get erratic pressure readings. If this isn't properly setup you could get some bizarre interruptions and interactions between pumps.

CoryH

@SuperJ , I feel like that might be happening, but here’s the problem. The install manual says the extra water feeder might be needed in certain situations, and all of the piping diagrams show an external water feeder. Also, if there was not an external water feeder then how would I purge the system?

CoryH

@Ironman , I’m still not following. When you say increase the size of the BB, are you saying just add more?

SuperJ

CoryH said:

@SuperJ , I feel like that might be happening, but here’s the problem. The install manual says the extra water feeder might be needed in certain situations, and all of the piping diagrams show an external water feeder. Also, if there was not an external water feeder then how would I purge the system?

I wouldn't remove it, just keep it closed unless purging or filling bulk water. Day to day you should need any makeup water so the boiler will be able to handle that internally. If you open up the system and drain some pipes, you can use the alternative fill path to speed things up.

hot_rod

Cory, spend the time to get that room by room load calculation accurate before you do or think about anymore adding or subtracting
Without that critical data, this is a big guessing game fo all of us.

Where are you located, we can look at the past weather data online to see what kind of a heating season is typical in your area.

bob eck

There is a reason a good professional heating contractor can make a fair living in this trade. It is because of their knowledge of how to size, install and do maintenance on all types of heating systems.
Doing a system like this yourself or going with the lowest bidder is not always the best.
What is the old saying it will cost you more money to have a professional contractor come in and fix a system the homeowner installed or a contractor installed for a very low price.
Most times you get what you pay for.

CoryH

@hot_rod im in southern New Hampshire. I will get that data again tonight and see if I come up with a different number.

Bob eck, I know what you’re saying, and all too well at this point. If you want some back story, we just bought the house in July expecting to do some light remodeling. Ended up finding mold, serious structural rot, serious plumbing leaks, structural failure, the list goes on. At this point I’m probably $50,000 in to this over what we paid for the house, and it wasn’t a good deal either. All of these issues were hiding behind the walls and could not have been found from the home inspection. It’s been a nightmare to put it lightly. So for financial reasons I’m trying to do as much as possible myself. I just never knew how much went into this particular project. Trust me, I know plumbers earn their wages, this **** is complicated if you don’t know what you’re doing!!!

Gordy

It is a science.

However finding a competent professional is also.......

Ironman

> @CoryH said:
> @Ironman , I’m still not following. When you say increase the size of the BB, are you saying just add more?

Yes, but concentrate on getting the heat loss calc right first.

Again, if you’d share your town or zip code, that would help us to determine if your numbers are close.

DanInNaperville

RE: I can’t touch directly above the tee because it’s so hot, yet the tee and everything downstream is cool due to the different temp water mixing.

Is the return line into the boiler also cool? If not, ignore what follows. :-)

If the return line to the boiler is cool, then your issue is that the internal pump or 3-way valve is bad (or some of the sensors and logic board that control it).

Make sure that you haven't set it to use an external pump. That setting doesn't mean you have an external circulator pump, it means that you don't want to use the boiler's internal pump (which you need to feed heat into the loop). The setting is on page 51 of this version of the manual (yours may be different).
https://www.ecomfort.com/manuals/noritz-96c4ecbf09a91f9bec4c93509492c885.pdf

You have almost no hot water coming out of the boiler if both downstream and return are cold, so the heat is not getting out of the boiler in heat mode. Your home's water supply acts as the "pump" to transfer heat from the boiler through a heat exchanger that also relies on the internal pump, so it's more likely that the issue is the internal 3 way valve.

CoryH

@DanInNaperville , checked my settings, all is correct.

I rearranged the piping, put the circulator a on the supply side so they’re now pushing, moved my water feeder to the supply side at the expansion tank, and combined 5 loops into 3.

Bad news is it seems to draw even less hot water out of the primary loop now. I throttled down the loop isolation valves to nearly shut and the hot water seems to drift into secondary, slowly, but I’m not super comfortable leaving it this way because the valves are so close to **** that they may actually be shut. I don’t want to burn out a circulator so I opened everything back up and instantly the pipe goes cold again.

I’ve redone my values on the slant/fin app and they’re quite similar to the first go. I don’t know if I’m doing something wrong, must be if everyone is saying they look way off.

At this point I’m at a loss. Any money I saved from trying to install this system myself I’ve blown with all of the rework. I think I’m going to throw in the towel and have a pro come see what they can do. My wife and kids are getting pretty tired of waking up to it being 55 degrees in the house and my electric bill was through the roof from using electric heater for the last 2 months.

Thanks for all the help and time invested in trying to walk me through this. You’ve all added something that made me a little smarter.

Anyone know a good heat guy in southern NH?!

DanInNaperville

Can you tell if the line going back into the boiler is hot?

If the supply going out from the boiler is hot but the line coming back in is not, then the 3 way valve inside the boiler is turned off or bad (or the control board is bad).
Sometimes those 3 way valves have a visible indication of how they're set.
Is the outdoor sensor connected properly? If there isn't a correct signal from the outdoor sensor, it can disable heating (the boiler is designed to not turn on when it's hot outside). if the outdoor sensor isn't working properly (or the control board is misinterpreting it) the boiler won't provide any heat.
From the rather limited illustration in the manual, I can't tell how hard it would be to remove the 3-way valve and test it. Before removing it, use a voltmeter to check that it's getting a signal to turn the valve to the heating position. You could also jumper it to force that position and see if it makes a difference.
You could remove the valve from the boiler and observe what it does when it's powered to switch from hot water to heating.
Also note that the boiler is designed to not be able to heat the house when there is hot water in use. If it (even if "mistakenly") thinks that hot water is being used, it shuts off the heat.

mattmia2

How do you know the secondary pumps are actually circulating water in the secondary loops? You need to get them mostly air free for them to circulate water, the pump is strong enough to push the water around, not to lift it through a pocket of air. If it is pex you should be able to see any air bubbles that are in there moving, especially if you shine a light through it.

CoryH

@mattmia2 , I know the secondary’s are working because the radiators get warm, they just don’t get hot because as I said earlier, the hot boiler water is mixing with the cold return water and cooling off so much that it just doesn’t heat a room.

@DanInNaperville , the primary return is cool, the same temp as what’s in the secondary loops. I’m not saying that it couldn’t be a bad three-way valve, I’ve not tried to test it, but I installed this unit brand new out of the box and it has been this way since day one.

mattmia2

Does it get hotter over time? The boiler will need to heat that mass of water in the secondary loops, but over time it should reach nearly the primary loop temp, assuming the primary loop is circulating. Is there a strainer anywhere in the primary loop that is clogged?

DanInNaperville

Going back to your original post, its seems likely that the 3-way valve is not opening for heat.
When you gated off the boiler loop and tried to run it with the external pumps, it should have worked fine (did you change the setting for an external pump?).

Either the system thinks there's a demand for hot water,
or it thinks it's too hot outside,
or the valve is broken,
or the controller board is broken.
If you can get one zone to warm up a little and it makes plenty of hot water, it points to the valve as most likely.
The noritz manual I found online doesn't have much detail on the 3 way valve and there's no full wiring diagram. If you can get at the thing, especially if you can remove it and make sure the valve isn't stuck, you'll probably be able to solve the problem. There may be some pipe shavings, teflon tape, pipe dope, or a chunk of rust in there blocking the valve. Or it was just DOA.
You might want to order a replacement, just in case. They don't seem to be too expensive.
Good luck with it!

CoryH

The water out of the boiler is 180*

It’s hot all the way until it meets the secondary loop where it immediately cools to about 100-110. I’ve let it run this way for weeks straight and it will not warm beyond that temp. My gut says that the secondary flow rate is far beyond the primary but I have no idea how to stop this. Throttling the valves seems to get hot water into the secondary but in order for that to happen I feel like there’s barely any flow and I’m concerned about burning out the circulators.

mattmia2

Oh, and look at the firing rate when the secondary loops are running, if it isn't firing at least 50% or so and the secondary loop isn't getting hot and the return is still well below the requested supply temp, the primary loop isn't circulating.

On an HTP with a similar control the firing rate is actually shown as the master boiler firing rate even though it is a single boiler system.(something I learned about 2 days ago after blindly guessing from it being the only thing that was sort of the firing rate listed in the parameters)...lookign at both the owner's and installer's manuals it looks like your only option to find firing rate is to clock the gas meter.

Gordy

@CoryH you must try to understand primary/secondary piping.

As long as the for your understanding we will call the primary loop the heating side, and the secondary loop the boiler side.

How much mixing in the p/s header will depend on how many gpm you are moving on the primary side verses the secondary side. For boiler efficiency “ so it gets the coldest return water to condense “ primary flow should be greater than secondary flow.

IF the 3 way valve is working properly.
IF the parameters are set correctly.
IF the system is purged of ALL air.

Your house is 55 degrees. It will take some time to get emitters up to temp. You are sending 55 degree water back to the boiler. All is not going into the boiler some will bypass the closely spaced Ts and mix with the supply from the boiler. You won’t get 180 out in the main supply until things start warming up.

Take a deep breath. I’ll trade you. I’ve been laying under my 01 Tahoe doing new ss break lines. I get to last one open the package, and the double flare fitting was cracked... thanks dorman.......

hot_rod

DanInNaperville said:

Going back to your original post, its seems likely that the 3-way valve is not opening for heat.
When you gated off the boiler loop and tried to run it with the external pumps, it should have worked fine (did you change the setting for an external pump?).

Either the system thinks there's a demand for hot water,
or it thinks it's too hot outside,
or the valve is broken,
or the controller board is broken.
If you can get one zone to warm up a little and it makes plenty of hot water, it points to the valve as most likely.
The noritz manual I found online doesn't have much detail on the 3 way valve and there's no full wiring diagram. If you can get at the thing, especially if you can remove it and make sure the valve isn't stuck, you'll probably be able to solve the problem. There may be some pipe shavings, teflon tape, pipe dope, or a chunk of rust in there blocking the valve. Or it was just DOA.
You might want to order a replacement, just in case. They don't seem to be too expensive.
Good luck with it!

Dan is on to something here.

A simple test, close off all the zone pump valves, allow the boiler to run, need to see 180 or whatever coming out, crossing the close tees and back into the return. if the return does not heat up , probably quickly, then the boiler circ is not moving that circuit for any of the reasons Dan mentioned. It could be as simple as a setting on the control.

Can you get Noritz tech support on the phone and walk thru the settings and troubleshooting procedure.

Or maybe they can recommend a factory trained rep or tech nearby.

http://support.noritz.com/contact.php


I really do not believe it is a piping issue.

CoryH

@Gordy , like I said, I ran it, untouched, for literally weeks straight. The unit NEVER stopped operating and it never got the secondary hot. I don’t think the problem is with my unit (although now I’m starting to think about checking out this 3-way valve, I did find a good amount of pipe dope in my air scoop screen...)

The secondary flow rate seems to be overpowering the primary.

CoryH

@hot_rod , didn’t see your last post until after I just sent my last one. I will go check the three way like you suggested right now and get back to you. If it’s something that easy my wife is going to kill me... hahaha

CoryH

@hot_rod , did your test, the return got hot in about 30 seconds. Much slower than I would have expected though. I have no level of experience with flow rates to understand if 30ish seconds computes to a restricted flow rate or if that would be considered normal. Seems slow to me (and yes, I have the pump on its highest setting)