New homeowner, living with Slant/Fin radiant heat

webercw

First winter in our house and just getting acquainted with our system. I grew up with forced air, so I've got a few questions that I'm hoping the community can help answer.

The system - 130 year-old home in Minnesota with Slant/Fin baseboard radiators installed at least 35 years ago, 2016 Slant/Fin Lynx 120CD condensing boiler that also feeds an Amtrol in-direct water heater. Controlled by a Nest thermostat.

1. The Slant/Fin Fine/Line 30 catalog claims heating elements that "stop pings and clicks" and "no-noise" expansion cradles". Maybe it's the age of our heating elements, but we certainly get pings and clicks throughout our house. Is that par for the course with baseboard radiators or a sign of other issues?
   
2. The previously owner said there aren't any bleeder points except for the air eliminator at the boiler. Is it possible he's right, or should I be hunting around upstairs more closely? I occasionally hear water running thought the pipes, so I'm concerned we've got trapped air hurting our efficiency. What can be done if I can't find a bleeder point and is there any real harm if I can hear rushing water?
   
3. Both the space heating supply water temperature and the supply to the DHW exchanger are set at the default of 176 degrees - well above the condensing temperature. Is there any explanation for this? Is there a simple way to determine the optimal temperature without doing a full load calculation? Is it as simple as reducing the temperature to the condensing point and seeing if I can hit my thermostat set point?
   
4. Related to the previous question - How long is reasonable for the boiler to run in order to maintain my set point (on a typical Minnesota winter day). How much higher should the supply temperature to the exchanger be compared to my desired DHW temperature?
   

Lots of questions, I know. Thanks for baring with me and helping out a newb.

Hot_water_fan

Is there any explanation for this? Is there a simple way to determine the optimal temperature without doing a full load calculation? Is it as simple as reducing the temperature to the condensing point and seeing if I can hit my thermostat set point?

Lazy installer, that’s all. You can find out your heat loss using your fuel usage or trial and error. The highest temps will be used when it’s coldest outside. You can likely condense the vast majority of the winter, even with baseboard. 

https://www.greenbuildingadvisor.com/article/replacing-a-furnace-or-boiler

 Here’s a fuel usage method. 

Related to the previous question - How long is reasonable for the boiler to run in order to maintain my set point (on a typical Minnesota winter day).

A typical winter day (let’s define as the middle 80% of winter days) with a modulating boiler could have 24/7 operation if sized correctly. Might not end up perfectly 24/7, but long run times aren’t bad. 

EdTheHeaterMan

As far as the clicking and pinging is concerned, there is always going to be copper pipe expansion an contracting when the water changes in the pipe. sending 140°F water into a room temperature radiator will cause rapid expansion of those pipes inside the radiator cover. The plastic cradel that the aluminum fins are resting on at every support bracket is supposed to allow the expansion movement to happen silently. You need to consider that a human being installed all those radiator covers and brackets so mistakes may have been made. Also if the pipe is long enough and does not have enough room to move without touching the wood that they go thru, then there is going to be some clicking and pinging that may not be from the actual radiators.

As far as the water noise inside the pipes, that is most likely air in the pipes. In many Baseboard Loop systems there are no air vents in the piping after those pipes leave the boiler room. A properly designed system will have an air elimination scoop in the boiler room to catch the air as it passes the boiler and collects it to be put into the expansion tank on older systems, or have a central air vent on newer systems with modern pre-charged expansion tanks. If your system was installed improperly, then your system design may not be controlling the air properly and you will need to purge the air manually. There are several YouTube videos that will explain the process.

Mad Dog_2

You still should be able to pull covers off and sneak some black Armaflex "donuts" under and against the metal bracket to make a cushion bewteen Element and brackets. Jimmy The Gent Burke taught me that on baseboard installs. We did a huge house, 3 zones on Long Island's Gold Coast in record time like 2 days. He was known as The Baseboard King and I just hung on for dear life and chased him 16 hours a day. He had me cut hundreds of 3/4" Armaflex "donuts" 2" long and put them every 3 feet or so so no rubbing would occur. Also on the Roughing, all pipe was insulated with seamless Armaflex (The Best) as we went long. Not a squeak, squeel or expansion noise!!! Mads Dog