Best Of

Re: Small boiler recommendation

Why does it have to go? Does your Mom agree ? Just a bit curious 🤔

The chamber is pretty broken up, the outer jacket has areas rusted away at the bottom, and there are areas inside that long brushes and saws just can't seem to get to (pin boiler) from the top or side access plates. I also can't get it much over 7% CO2 without it smoking and the stack temp is over 600F gross. The AF is also some 30 plus years old (I didn't install that burner and don't even know if the head is even a correct match for that boiler), and the old Honeywell controls are archaic (the Honeywell aquastat board burned a hole through it and I had to rebuild that a couple of years ago). I also think that when I have to sell the house in a few years that big ugly chunk will be a big liability and will flag a house inspection.

Mom doesn't care and pretty much defers repairs to me and my brothers. As long as there's heat, mom is happy.

MaxMercy

4

Re: Combustion analysis startup calibration question

Outside, always calibrate the unit outside, and not right next to your running vehicle, generator, equipment etc.

GGross

3

Re: Combustion analysis startup calibration question

I am more concerned with my safety than a bogus combustion efficiency calculation. If your analyzer zeroes out the CO during calibration then it needs to be turned on outside, 30 degree in temperature affects the efficiency 1%. Not enough difference to sacrifice safety. Some people should not be teaching when they are teaching how to endanger yourself.

captainco

4

Re: Is the heat loss calculation linear --at all?

The design day temperature he used, was a modestly cold number but nowhere near the record. I recalculated it based on the record outdoor low temperature but used a linear relationship to the delta T.

A bit surprising perhaps, but you should not use the absolute coldest temperature. You use the design temp.

If you are sizing conventional fired systems, using the design temperature is what to do. This usually will cover 98% of the heating season. However, if using heat a heat pump, its much more complicated. The problem is that as you drop below design temperature, the heating capacity of the heat pump is steadily dropping I.E. ....Here in Chicago, the design temperature is about 0F, However, we have hit -25F as records. A fired system that is designed right on will be able to keep a building warm at 70F when it is 0F outside with let's say 100,000 btu/hr, so for the most part it will be able to maintain the building at 45F if it is -20F outdoors ( more or less, depending on ground contact tempering for example), also needing 100,000 btu/hr. However, with a heat pump, when you're below design temperature (0F) the heat pump capacity is now lower, so you can no longer producing 100,000 btu/hr so you can no longer maintain a 70F differential between the outdoors and indoors. The interior temperature will now drop lower than the 70F differential. This issue seems to currently be ignored in design calculations. As an example, we have a client that had a Heat Pump system installed to heat a large space. They could heat to 70F when it was 0F outdoor. However, when we had some extreme extreme outdoor temperatures ( -10 to -12F) a year or two ago, and they could not get the building above 40F. I have not been able to find what the COP is for a heat pump at 0F versus -25F, but I bet it is quite significant in a percentage or reduced heating capacity.

The Steam Whisperer

1

Re: Wiring old hydronic gas boiler as backup for new heat pump

@litedesign you'll need your heat loss. Usually 32F is picked by contractors because it's when water freezes, not because it's a relevant balance point. Basically, you first plot your heat loss. It's a linear function of outdoor temp, as it gets colder it increases consistently. Then you plot your heat pumps operating envelope, which works in reverse - as it gets colder, it outputs less. It's usually not linear though. Idronics describes it better than I can.

If you're interested, you can probably find your Bosch's on the internet. Where the heat loss = heat pump max output, that temp is the balance point. You can try trial and error - lock out the boiler and see at which temp the heat pump can't maintain the thermostat. There's another topic called the "economic balance point", which is the point when the heat sources are equal in cost. That's much harder to find and often isn't worth the effort since gas prices changes frequently and efficiencies vary by temperature.

https://www.caleffi.com/sites/default/files/file/idronics_27_na.pdf

Hot_water_fan

2

Re: Combining baseboard and in-floor temperature issue

Hi hotrod. Based on what has been posted here, I thought I had all the highlights met. Primarily having the radiant return feed the cold side of the 3way, having a circ pump on the mix side of the 3way, having the radiant return after the 3way join up with the baseboard return on its way back to the boiler and moving the other circ pump so it only feeds the baseboard loop. What is wrong? What other components am I missing? I am not clear on what a primary secondary header is.

AlanRadiantHeat

1

Re: Young People - The Smart Phone Generation

I just can't think of any reasons why young people would avoid the construction/mechanicals trades...must be something wrong with them

Social stigma, risk of injury/cancers, lack of trade schools/summer jobs/learning from parents about trades that would interest them.

Middle and High Schools don't focus on any kind of exploration of trade work, they push everyone to aim toward going to college.

Vocational education used to be a larger part of public education and it fell by the wayside thanks to Department of Education policy sine its inception and general push by Congress during the Cold War to push everyone towards college thinking that it would increase the number of scientists & engineers without at thought that doing so could compromise the industrial/skilled trade base.

Employers also used to be able to test applicants for technical skills and do more in-company training for various skills similar to the military. Then there were multiple court rulings challenging these tests and in-company credentials, which lead to the gate keeping and credentialism being outsourced to universities or third party trade/occupational associations with a vested financial interest in shrinking the labor pool.