Help choosing a new boiler (Part 3 - the Results! and more questions :)
Hello forum,
For anyone wishing to follow along, here is Part 1 (me stating my situation and asking for help figuring out what sort of boiler to buy) and Part 2 (narrowing down my options) and a bonus question (me trying to figure out where to put the exhaust).
TL-DR; My 30-year-old cast iron boiler died, so I needed to pick some replacement in a hurry. My water heater tank was also 30-years old, but still working, so I had to decide to replace it or not, and if so, with what. I had been quoted for combi-boilers and decided to come here and get advice. I ended up choosing an IBC SL10-85 modulating boiler (output range: 10,100 BTU/h to 79,000 BTU/H) with a 40-gallon indirect water tank for a home with just under 50,000 BTU/H design heat load.
Behold:
Special requests: anti-vibration mounts (though this boiler is actually so quiet), mixing valve for the hot water tank so I can store the water at a high temperature (apparently this is standard), dirt screen with magnet (apparently also standard), and exhaust through the existing chimney instead of basement wall (on the other side of the wall from the boiler is a patio area).
I am very happy to have central heating after 3 weeks of space heaters! Just want to thank everyone for your help and thought you'd like to see the outcome! (Feedback or things to watch out for, are welcome).
As expected, though, it seems to need tweaking.
Issue: the hot water isn't hot. I am hoping this is something I can fix myself rather than having to wait until Monday and call the guys to come back.
DHW at the faucet is about 85 deg F on hottest setting. I would describe this as.. lukewarm. DHW tank is currently set at 140F so I am told; was planning on increasing to 160F after the house had a chance to warm up. Which brings me to my second point.
House heating takes FOREVER. I increased the thermostat from 19C (66.2F) to 21C (69.8F) two and a half hours ago, and so far we've only managed to get to 20C (68F). Is this.. normal? (I'm used to a one-setting boiler firing all 80,000 BTU at my baseboards for like 5 minutes and being done lol)
Yesterday when we kicked the system on for the first time, it took four hours to go from 19.5C to 21C, and the installer explained it was taking a while because it had to work out the air in the system. I did not bleed any radiators, but they all feel warm (well, lukewarm..) so I think they should be good by now? It's been 15 hours? There is also an automatic bleeder installed. So I'm thinking the boiler water just isn't hot enough, like the DHW.
I haven't read the encyclopedias that came with it yet, but just wondering if this is something in the settings that I can do, or if I have to call them to come back.
Comments
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" it took four hours to go from 19.5C to 21C, "
That is actually what you want, means the system is running well and was set up correctly. The boiler should only be supplying hot enough water to match the heat load of the house. For night time setback, set it to start earlier so it will meet your target when you need it.
The cold water is a mixing valve adjustment. These have a cap you can loosen and unlock which lets you turn to adjust the temperature. If this doesn't work sometimes the check valves inside the mixing valve can have crud in them which needs to be cleaned out.
I would not crank the tank temperature more than 140F. Indirects have very quick recovery and your boiler has enough heat output to run about 1 shower continuously. I doubt you'll have issues with the temp as is.
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Oh no!!!! So when I wake up in the morning and turn the heat up, it will be nearly lunch time before my house is warm? That's… not good news to me. 😔 I guess I will need to keep the electric space heaters around forever
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Hot water should be stored above 140F, to avoid potential Legionella: CDC
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your old boiler was probably running 180f all the time. They can adjust the ODR on this one to get a bit quicker response. A pic pic of your mixing valve, some of them have tamper proof caps that need to be removed to adjust them up higher
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0 -
So adjusting the ODR can make my house warm up faster? Is this something I can do? (also what is ODR)
This is my mixing valve: Watts LF1170
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I just Googled it; the ODR means outdoor reset. The boiler supports outdoor reset but it was not installed. (I asked about it and they said they usually don't install them, and I was good with that.)
Does that mean I am stuck with 4-5 hour wait for temperature increases? 😥
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They set heating to 131? I think it needs to be higher.
if you want to take the time to read through the programming section of the manual it will tell you how to change the setting.
Usually the installer will write the settings in the manual as to how they programmed it
turn the red knob to hotter. It should supply 120f . If the tank is at 140? But it looks like they set your dhw to 133, it may need to be hotter for that mixing valve to regulate to 120Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream1 -
For the first part, are you referring to the space heating or the domestic water heating?
I increased the DHW tank temperature setting to 155F. The boiler has heated it but the tap temperature is still not hot.. looks like it's maybe around 90F now or just under.
The mixing valve's documentation says it's set at the factory for 120F and should only be set by a qualified installer 🤔
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ODR is something that is beneficial to you. It can save about 15% on fuel and actually make the house more comfortable. All they have to do is install the outdoor sensor and properly adjust the reset curve.
When using it, you don’t want to be setting the thermostat up and down because the response time will be much longer and it will probably use more fuel. It’s old technology vs. new. You now have a boiler which modulates to match the load when properly set up. The old one was just 100% on or 100% off.
As mentioned, the mixing valve on the domestic needs to be adjusted to get hotter water.
Bob Boan
You can choose to do what you want, but you cannot choose the consequences.1 -
The mixing valve may be set to 120°F at the factory, or it may be a little off. I have had that problems with other customers that like to take a shower with 125°F water. the standard Mixing valve has a stop at 120°F and if your valve is already set there and the temperature sensing spring is out of calibration, then you will never get the hot water that you want. You may need to get a different valve that has a different temperature range like this one
EDIT: Have the valve you already have checked for the proper adjustment and to see if there is any debris lodged in the valve the is preventing the valve from closing the cold water off enough to get you the 120°F water you want.
New systems often have junk inside the pipes that foul thing up and need to be cleaned out.
Edward Young Retired
After you make that expensive repair and you still have the same problem, What will you check next?
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Oh, I see. Actually that probably explains why they didn't install the outdoor reset then. I wanted to be able to lower the home's temperature at night (or when I'm away) and then raise it during the day. Maybe I will get one of those programmable thermostats so the temperature can start increasing a couple of hours before I wake up :)
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Huh. Okay. I think I will call them on Monday then. I feel like I could try to set this myself, but with the wording in the manual that came with it, that it should only be adjusted by a qualified installer, I'm concerned about voiding any kind of warranty it may have, or they won't support it after I monkeyed around with it. Especially if, like you said, it needs to be replaced.
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At least the home is warm now!
As far as adjusting the max temperature for space heating or central heating (CH) in order to get the most out of your equipment you want it to operate at the lowest possible temperature. In order to get your system to operate the way the old one did, you need to operate it at 180°F. You may want to try a temperature somewhere in the middle to split the difference. Like start at 140° to see if that is more to your liking. if not then go to 145°F a few days later. Eventually you will find a nice compromise.
Edward Young Retired
After you make that expensive repair and you still have the same problem, What will you check next?
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I will add one thing about your boiler, or any boiler for that matter. You need the proper size boiler to be able to heat your home on the coldest day of the year (sometimes called the design temperature, but that is not always true, it sometimes gets colder than the stated "DESIGN" temperature for your area). That said, you don't need that much heat on any given Tuesday when the overnight low is only 2°C. That will only need about half the capacity of that new heater. The best way to keep that heater operating at the lower capacity is with a lower water temperature pumping through the radiators.
Since those lower water temperatures in the radiators will keep your home comfortable, then there is no need to use hotter water in the radiators on the milder days of the heating season. The problem with that is the lower temperature water will not increase the room temperature as fast as you would like. In order to get you the result of a lower room temperature while sleeping and a higher room temperature while awake, you could use a learning thermostat that will consider the outdoor temperature when changing from the low setting to the high setting and start the process 4 hours before you want the higher room temperature on very cold days and only start the process an hour ahead of time before you want the higher room temperature on milder outdoor temperature days.
Honeywell, Nest, and ecobee are three companies that make such a thermostat.
Edward Young Retired
After you make that expensive repair and you still have the same problem, What will you check next?
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Thank you, this is great info!!
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That’s not the approach to use if you want the best efficiency and comfort. That’s the way it was done with the old technology boiler that you previously had.
With the new boiler, that approach actually fights with how your new boiler is designed to operate. The new boiler modulates its firing rate and the water temperature (when the outdoor sensor is connected) to match the ACTUAL load on the house. Running the thermostat up and down is counterproductive to that.
Get the installer to come back and connect the outdoor sensor and set the ODR curve to match the type of radiators that you have. Then, set the thermostat at one temperature at which you’re comfortable and leave it there.
You paid for a boiler with ODR and that’s what you should have. That’s the most efficient way to run that boiler - and the most comfortable.
Bob Boan
You can choose to do what you want, but you cannot choose the consequences.
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Get the installer to come back and connect the outdoor sensor and set the ODR curve to match the type of radiators that you have. Then, set the thermostat at one temperature at which you’re comfortable and leave it there.
Sadly, as you know, this is an exercise in futility and no contractor wants to even think about bothering to set it properly (and they generally cannot without more data and iteration). The H/O needs to understand and adjust it……………if the contractor would take the time to explain it.
I takes weeks of small adjustments to dial it in properly, and even in that scenario, it could be slightly off at the extremes of OAT.
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To get it perfectly adjusted, maybe; to get it reasonably close, no.
Anything close is better than nothing.
As I stated previously, it’s a function of the boiler that supposed to be used and the contractor sold it as such. He should be honest and competent enough to do it or else he should not be selling the boiler. It’s not rocket science.
Bob Boan
You can choose to do what you want, but you cannot choose the consequences.1 -
It’s not rocket science.
Excuse me…………😅
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I have an IBC boiler, absolutely love it. I don't have have an Outdoor reset either but I run it at 158*F and when it gets really cold I bump it too 165*F. Get a degree an hour rise easily on the coldest days.
DHW is set at 125*F and mixing valve kicks it down to 120*F endless showers
You just gotta dial that thing in, you will love it!
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This is exactly my experience with the Lochinvar Knight boiler I had installed (in another house) back in 2009. I had to tweak its program for months before it worked right. (And I may be misremembering, but I think I had them remove the outdoor reset eventually - maybe).
Unfortunately as a human (especially a female one), I don't prefer one constant temperature for 6 months straight just because that's the ideal thing for my boiler's design. It would be great if boilers were actually designed for the comfort and convenience of the people in whose homes they were installed. Sometimes I want it cooler, sometimes I want it warmer. And humans evolved with cooler temperatures at night - cooling down helps us make melatonin for sleeping. But I hate freezing during the day, at which time I am not normally bundled up under covers.
As for the boiler sales people.. well they can only sell what is being manufactured and what is dictated by local codes. For example, where I live, all new heating systems have to be high-efficiency (more than 90%), so a mod/con was my only option. If I had a choice, I probably would have bought another cast-iron on/off boiler - but I didn't. Our jurisdiction even gives out programmable thermostats to encourage people to turn it down at night or when out at work.
As for my DHW/mixing valve question, I just went down and tried to see if I could do anything; it turns out there is a screw that you need to remove, using a specific size of Allen key I don't have. So my water will remain tepid until next week when the installers can come back. Sigh.
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You are completely accurate in your analysis.
If you are an individual who wishes to adjust the temperature in various rooms YOURSELF and have it recover to your new set temperature in a REASONABLE amount of time, outdoor reset is NOT FOR YOU.
However, you CAN and SHOULD learn how to change the boiler supply temperature. You might want it at 165F in the coldest month of the year but would be perfectly pleased with 145F in November and will will be perfectly pleased with 130F in October. You can make these changes YOURSELF in about one minute after 10 minutes of instruction by the installer. LEARN how to do it and save fuel and longevity for the boiler.
Note that I am simply guessing at the temperatures. Yours might be a bit different and that requires experimentation.
Or, you just leave it at 180F year round and burn extra fuel for no reason. But, the recovery after a 10F setback will be just like your old boiler………….FAST.
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up for a learning experience ?
NTI has videos on how to program their boilers . If the installer cannot or will not you could learn the settings and do it yourself. You need them to wire in the sensor however.
Or call the NTI rep in your area, find the contact info at the NTI site. Tell them the installer doesn’t want to connect the ODR on you newly installed boiler
Have the model and serial number ready
Ill bet the local rep would be happy to help you get it adjusted
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream
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As others have said, you want outdoor reset.
The typical dialed in curve is not for you though, but that can be easily adjusted to allow for faster recovery. The curve with faster recovery will still save you a significant amount of fuel in the shoulder season, this is free money in your pocket. There is no need for fixed setpoint. The best part is that once you have the curve selected that works for you, you don't have to do anything, it all happens automatically.
Running a modcon in fixed temperature mode is throwing all that efficiency you paid for out the window.
P.S. Once you get your mixing valve fixed, turn down the tank temperature. The only need for 160F water is if you keep running out.
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Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0 -
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0 -
contacts, if you need to go this far
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0
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