New Boiler can't maintain temperature in house

dneubauer09

Hi all.
I am a homeowner, not a professional. Forgive any errors I make in explaining what's going on!

Setup:

• 1500sqft, 2 level home plus unheated crawlspace
  
• boiler resides in crawlspace
  
• Baseboard radiators running outside perimeter of 1st and 2nd floor, emitters only under windows
  
• Each floor is on it's own loop, controlled by zone valves
  
• Thermostats act as on/off switch for the zone valves, boiler kicks on when valves are opened, off when closed
  
• There are no circulator pumps in the system, only the built-in circulator pump in the boiler is present
  

Background Information:
We had a Triangle Tube Prestige Excellence 110 combination boiler replaced with an NTI VM110P yesterday.

The previous system was getting old and we were facing constant breakdowns. In a bit of frustration we had our HVAC contractor replace the system with the NTI.

Our old system heated the house well, we could set the temperature to whatever we wanted and in a couple hours, it would be there.

The new system is struggling to get the house up to temperature, and it is only ~35F outside. I worry with colder temperatures it will not be able to keep temperature at all. We turned the system on at 66F in the house and after almost 24 hours we only just got to 70F in the house. Old system would have taken 2-3 hours for this.

Questions:
If you navigate to this link, page 27 of the PDF (marked as page 20 ON the page itself), our old setup matched exactly figure 11:
https://www.triangletube.com/getmedia/7319269b-3e7d-4f34-87e3-3d66fafe30eb/PS-EXCELLENCE-Installation-Manual.pdf?ext=.pdf

Our new setup is identical to this, except the contractor installed a low-loss header between the boiler supply and return.
If you navigate to this link, page 48 of the PDF, our new setup matches this (only 2 loops, not 3), except for the CH Circulator pump, that is not present:
https://ntiboilers.com/wp-content/uploads/2018/12/Vmax-Installation-and-Operation-Manual-pn-85171-1.pdf

As I've been reading up on this, it seems this low loss header may be causing my problem. As the built-in circulator runs, the supply water can simply bypass the zones through the low loss header and go straight to the returns.

Since we do not have additional circulator pumps, I'm thinking to tell the contractor to remove the low loss header.
The other option would be request he install a circulator pump as indicated in the installation guide, but that seems like it might be unnecessary if we remove the low loss header.

Any opinions on this?

Jamie Hall

Low loss header? No secondary circulating pump (the CH pump)? Well, your surmise is quite correct -- there's no reason for the water to go through the heating system and so it doesn't.

What was the installer thinking? Um... was he thinking?

The purpose of that setup -- with the pump -- is to be able to deliver a nearly constant flow of water to the radiation, at a temperature which allows the radiation to heat the house, while the boiler operates at a flow -- sometimes more, sometimes less -- which allows it, in turn, to operate as efficiently as it can. If you want to get the best efficiency and operation that that new boiler can produce -- and why not? you paid for it -- you have to have that secondary CH pump (although I personally would prefer to have a pump for each zone, and skip the valves). That pump -- or pumps -- could be controlled in a variety of ways, some more sophisticated than others.

Get someone in there who knows what he or she is doing and set it up properly.

dneubauer09

Jamie Hall said:

Well, your surmise is quite correct -- there's no reason for the water to go through the heating system and so it doesn't.

Thanks for confirming my theory is correct.

Jamie Hall said:

(although I personally would prefer to have a pump for each zone, and skip the valves). That pump -- or pumps -- could be controlled in a variety of ways, some more sophisticated than others.

Can you elaborate on this? The old setup had the valves because the internal pump handled all the flow (no low-loss header)

Do the pumps have one-way valves so that you cannot backflow into the other loop if it's not on?

Currently we use Nest thermostats to control the valves (simple on/off switch really), would that work to control pumps in the same manner?

I imagine at this point, a better contractor would know what's going on.

I will give my guy the benefit of the doubt (for now) that we were without heat for nearly a day when he got there, and he worked as quickly as he could to keep us from freezing out.

He'll be by tomorrow and I'll propose this info to him and see what he says.

HomerJSmith

- 35 degs, how's it getting any colder than that? hmmm

I always plumb in a primary-secondary manner even if the manufacturer says one pump can do it all. With zone valves, my choice of a primary pump (not the boiler pump) is an ECM pump.

Jamie Hall is correct. Why would the heated water go to the emitters? Water is weak kneed, it takes the path of least resistance.

Note: Verify CH circulator is properly sized to overcome the system pressure drop and provide adequate flow through the boiler system.

The operative words are "properly sized". It seems to me, yours are not.

dneubauer09

HomerJSmith said:

- 35 degs, how's it getting any colder than that? hmmm

I always plumb in a primary-secondary manner even if the manufacturer says one pump can do it all. With zone valves, my choice of a primary pump (not the boiler pump) is an ECM pump.

Jamie Hall is correct. Why would the heated water go to the emitters? Water is weak kneed, it takes the path of least resistance.

Note: Verify CH circulator is properly sized to overcome the system pressure drop and provide adequate flow through the boiler system.

The operative words are "properly sized". It seems to me, yours are not.

~35F, not -35F, "~" meaning "about"

And yes, I would imagine the fact I have no secondary pump is the definition of NOT "properly sized".

Appreciate the response!

dneubauer09

Also, it is interesting because the radiators throughout the house DO get hot. Hot enough that I cannot touch the copper piping for more than a few seconds. Just the intensity of the heat coming off the emitter parts is not there.

I have to assume with more flow through them that the intensity of the heat would increase?

hot_rod

be good to know what temperature is going to the fin tube. 140F can feel hot to the touch, you may need 180F however.

HomerJSmith

Well, is it possible that the outlet temperature of the water, set by the boiler programing, is too low?

dneubauer09

hot_rod said:

be good to know what temperature is going to the fin tube. 140F can feel hot to the touch, you may need 180F however.

I took a reliable meat thermometer to the first emitter on the 1st floor and it hit about 155F, the last emitter in the loop hits about 115F
Haven't checked 2nd floor at all.

Output at the boiler itself will match the set point, I have seen it approach 200F on the analog gauge (hard to tell exactly, it is not a great gauge) installed in the low-loss header, which matched the setpoint at the time.

HomerJSmith said:

Well, is it possible that the outlet temperature of the water, set by the boiler programing, is too low?

Setpoints programmed in the boiler are:
0F and below outdoor temperature: 190F
70F and above outdoor temperature: 140F

Both of these are the max advised in the manual for baseboard radiators.
There are no other setpoint settings available on this boiler.
I also have it set to increase the set point by 10F every 15 minutes of continuous CH call, as advised by NTI over the phone via the contractor.
Since it is not able to keep temperature, the call is continuous anyway, so the set point ends up being the 190F.

Jamie Hall

An emitter at 115 isn't going to emit much. And the temperature difference from end to end is indicative of relatively little flow. Coupled with the boiler hitting setpoint... you're just not getting much flow out where you need it.

But we knew that...

EdTheHeaterMan

Did you get the new circulator in the Space Heating loop yet? All the speculation is nice but if the water is not circulating thru the baseboards, why bother discussing solutions other than the one in the instruction book? Get a Circulator installed. You have a choice but a Taco 007F (or equal) is an economical way to go. (Get flanges with valves for easy service later on). On your system, anything else is overkill and won't amount to much of a difference.

dneubauer09

EdTheHeaterMan said:

Did you get the new circulator in the Space Heating loop yet? All the speculation is nice but if the water is not circulating thru the baseboards, why bother discussing solutions other than the one in the instruction book? Get a Circulator installed. You have a choice but a Taco 007F (or equal) is an economical way to go. (Get flanges with valves for easy service later on). On your system, anything else is overkill and won't amount to much of a difference.

The new boiler was installed yesterday and the contractor is coming tomorrow morning.
I really appreciate all the knowledge shared/confirmed here. It will help me seek out whether my contractor is BSing his way through this and whether I need to find someone else.

Ideally I'd love to DIY this, as that's the kind of person I am, but in the mean time it is cold out and my house is barely 69F right now, so alas I must trust a contractor!

EdTheHeaterMan

@dneubauer09, Open the book to the page you described and circle the circulator pump you said was missing. leave it open on or near the heater. Add a note that says "Please show me where this circulator is" If you still have the final payment due, Don't pay it until you are satisfied.

That boiler can operate at lower temperatures and provide more heat than you are getting now if the pump is there.

dneubauer09

EdTheHeaterMan said:

That boiler can operate at lower temperatures and provide more heat than you are getting now if the pump is there.

I don't doubt that for a second. Our Triangle Tube boiler used the internal pump to do this work and it cranked out a TON of heat into the home (when it wasn't broken).

I will get my contractor to install the pump, and if he can't do it I will get someone else.

That Taco pump you referred to, is that an ECM pump (it appears not to be)? The manual warns to relay an ECM pump to avoid premature failure of the boiler's electrical contacts for the pump.

EBEBRATT-Ed

He (the installer) turned it into a gravity job LOL

EdTheHeaterMan

The maximum load for the CH pump and the BOILER PUMP is not to exceed 2.7 amp. The Taco 0075F draws only 0.71 amps. I see no problem using that pump. If you feel better with the ECM pumps you may want to ask the installing contractor about it. But I would provide the Taco 0075F as my go-to bulletproof part for zone valve systems. They do fail from time to time (rarely)... But I have had good luck with them because I always installed them the way the factory recommends. The motor shaft on the horizontal plane. Easily done with "adjustable isolation valve flanges".

dneubauer09

Can any of you confirm my calculations here for circulator pump need? Again I am trying to head off ensuring the contractor is doing this right..

My heating loops runs the outside perimeter of my home. I measured 2 walls and got about 24' each, so roughly each loop is 96', let's round that to 100'
I am not including the height because it is closed loop (see here why I am saying this)

Measuring the copper piping in the loops, it appears to be 1" OD.

Using this link I came up with the following measurements:
https://heatinghelp.com/systems-help-center/how-to-size-circulators/

Flow: 8gpm (based on 1" copper piping)
Head: 6' (based on 100' loop length)

What I'm not sure of though. This head calculation is based on 1 loop, not 2. I am intending the contractor to only install a single pump. If both loops are active, would the calculation be based on 100' or 200'?
If it were 200', the head would be about 12', not 6'

Looking at Taco's performance curve charts, if I am at 6' of head, I can go with a 007.
If I am at 12', I would need maybe a 0010 or 0012 (hard to tell from the chart, I'd have to confirm the actual models).

Thanks again for all the help everyone!

Jamie Hall

100 feet. If the loops are plumbed in parallel, the flows add (subject to the pump's performance) but the heads don't.

dneubauer09

Great, thank you @Jamie Hall

I also am realizing that my piping is probably 7/8" OD, which would make it 3/4" pipe.. Thus the flow rate is 4gpm.

Flow: 4gpm
Head: 6'

Seems the Taco 007 that @EdTheHeaterMan suggested would be suitable (albeit slightly oversized) but it appears to be most common from what I'm reading.

hot_rod

With a zone valves system look at one of the ECM circulators set in delta P mode. It will adjust it's output to the loads near perfectly.
Taco, Grundfos, Wilo, B&G all have ECM style available.

EdTheHeaterMan

I agree with Bob on this, however, this is not a 5+ zone system with flow rates of 20+ GPM full flow down to a less than 3 GPM single-zone calling condition.

I just read the article about almost famous quotes and I would submit "For a difference to be a difference it needs to make a difference." Will the expensive $$ pump yield a significant difference here? What if you need to replace the pump after the warranty is over? We will never know if the Little Red, the Grundfos UPS-15, or the Taco 007 would have worked just fine.

Since the Taco 007F5 has been the OEM choice for over 4 decades, I submit that it is a viable choice here.

Respectfully submitted
Mr. Ed

EdTheHeaterMan

@dneubauer09 Be sure to let us know how everything works out at the end of the job. Pictures too

hot_rod

EdTheHeaterMan said:

I agree with Bob on this, however, this is not a 5+ zone system with flow rates of 20+ GPM full flow down to a less than 3 GPM single-zone calling condition.

I just read the article about almost famous quotes and I would submit "For a difference to be a difference it needs to make a difference." Will the expensive $$ pump yield a significant difference here? What if you need to replace the pump after the warranty is over? We will never know if the Little Red, the Grundfos UPS-15, or the Taco 007 would have worked just fine.

Since the Taco 007F5 has been the OEM choice for over 4 decades, I submit that it is a viable choice here.

Respectfully submitted
Mr. Ed

certainly the 007 is one of the better circs for ZV systems. I suppose if we knew the requirements of each zone we could talk more knowledgeable, develop a system curve. If i were a betting man, I'd say a single zone could be 1 gpm or less, putting the circ in one of the least desirable conditions, the extreme end of the curve, possibly a wire to water efficiency (71W moving 1 gpm), maybe 5% efficiency?

Check around in some areas there are rebates for ECM upgrades, you might get a 007E or equivalent for way less than an 007? My boss replaced 6 in his house for 25 bucks each after rebates.

Robert_25

EdTheHeaterMan said:

I agree with Bob on this, however, this is not a 5+ zone system with flow rates of 20+ GPM full flow down to a less than 3 GPM single-zone calling condition.

I just read the article about almost famous quotes and I would submit "For a difference to be a difference it needs to make a difference." Will the expensive $$ pump yield a significant difference here? What if you need to replace the pump after the warranty is over? We will never know if the Little Red, the Grundfos UPS-15, or the Taco 007 would have worked just fine.

Since the Taco 007F5 has been the OEM choice for over 4 decades, I submit that it is a viable choice here.

Respectfully submitted
Mr. Ed

The 007F5 is certainly a viable choice, but if the OP wants something with a flatter pump curve and/or lives somewhere with high electric rates, I would take a look at the 007E...it is about $40 more.

dneubauer09

Well it looks like this saga is over.

Contractor installed the circulator as advised in the manual and the temperature in the house came up within a couple hours.

Now that I know everything works and I am not going to be left in the cold, I am wondering how I can ensure everything is working as efficiently as possible (within reason).

I dropped the set points back down to the minimum recommended for baseboards (110F @70F ODT, 160F @0F ODT).
These settings seem to be working just fine at maintaining the home at the thermostat set temperature.

I did happen upon some articles advising to avoid using set-back thermostats, as these modulating condensing boilers like to heat slowly at low temperatures rather than fast at high temperatures.
Really I just want to make sure I am utilizing the condensing functionality.. How might I accomplish that?

Jamie Hall

As you say -- mod/cons will work at their best when they are running at as low a temperature as they can to just heat the space. May take some fiddling.

The trouble with setbacks -- especially bigger ones -- is that the boiler has to run harder to get the temperature back up, and that takes them away from their best operating point. The unsolved question is... does the fuel you save from a cool house for a few hours outweigh the extra fuel used to get the temperature back up? Endless debate!

dneubauer09

EdTheHeaterMan said:

@dneubauer09 Be sure to let us know how everything works out at the end of the job. Pictures too

Contractor put in a Grundfos 15-55F. It's in "AutoAdapt" mode, which seems to run at about 3-4 GPM and about 15 watts, of course it modulates down. I see it running 1 GPM and 5 watts often.

Best choice pump or not, that's what he installed, and what I am now stuck with.

EdTheHeaterMan

Good choice by the contractor. the Variable speed is more than the minimum requirement. You have a good system now. Grundfos is a good choice.

I believe that have solved this problem, but back in the day... Grundfos circulators would get stuck over the summer when they sat idle for several months. In the past, I have returned what I Thought was a defective pump only to find out (at the supply house) that there was a small screw cap to access the rotor with a pocket screw driver to give the rotor a spin. The pump would run fine the rest of the season.



Is this a good thing, Yes if you know about it? If you have trouble with the pump next season, you may just need to give it a push!

Robert_25

dneubauer09 said:

@dneubauer09 Be sure to let us know how everything works out at the end of the job. Pictures too

Contractor put in a Grundfos 15-55F. It's in "AutoAdapt" mode, which seems to run at about 3-4 GPM and about 15 watts, of course it modulates down. I see it running 1 GPM and 5 watts often. Best choice pump or not, that's what he installed, and what I am now stuck with.

Great choice.  

hot_rod

EdTheHeaterMan said:

Good choice by the contractor. the Variable speed is more than the minimum requirement. You have a good system now. Grundfos is a good choice.

I believe that have solved this problem, but back in the day... Grundfos circulators would get stuck over the summer when they sat idle for several months. In the past, I have returned what I Thought was a defective pump only to find out (at the supply house) that there was a small screw cap to access the rotor with a pocket screw driver to give the rotor a spin. The pump would run fine the rest of the season.



Is this a good thing, Yes if you know about it? If you have trouble with the pump next season, you may just need to give it a push!

Ed, I've found some, not all, still have that screw hidden under the full label. I wonder that it accessible screw disappeared due to liability concerns? You have probably experienced steam come out of those bleed ports from an over-heated or cavitating circ.

It's great for folks that understand the concept, maybe not so much for DIYers and HOs.