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Radiant Loop Using Cast Iron Radiators
Hello All. I am Installing a new hydronic radiant heating system in an existing home that is currently "gutted" of most drywall and interior finishes. The home is two stories, about 22 years old, and built with modern materials and methods. I have decided to use cast iron radiators for the emitters and each floor will be its own independently controlled zone on its own loop using a reverse return, 2 pipe system. I have already done a thorough heat loss analysis and sized the radiators required for each room. The loop for the first floor will be in the basement with the supply and return to each radiator going up through the floor. The loop for the second story will be run along/though the second story floor joists between the first floor ceiling and second story floor with the supply and return for each second story radiator going up through the second story floor. The piping for the first floor loop (in basement) will probably be copper, and the loop for the second story will have to be pex since I am going to have to drill each floor joist and "fish" it through each one 16" O.C. My question is: in this scenario how does one get the water from the supply loop up and into the radiators? The floor joists in both cases are 2x10s so the supply water will have to be pushed up about 15 inches into the radiator and radiators are 25" tall so approximately 40" of elevation difference. My guess is If I use regular tees for the supply and return to each radiator the water will never exit the supply loop. How is this typically done? Thanks in advance for any responses.
I will add I have sized and installed several radiant concrete floor slabs that work flawlessly but I have never messed with these cast iron radiators yet.
Re: Boiler pressure constantly rises to/past 30psi relief valve trigger
The contacts in the electricals may have gotten oxidized and stopped working. Then when you twiddled the dials, you may have broken through the oxidation and re-made the electrical contact.
Yes, you can also reduce the water pressure. For only a 4 foot lift you can get away with under 10 psi, but the less air pressure you start with, the less you can afford to lose by normal leakage. So check it at least annually and add air as needed.
jesmed1
Re: Purging Questions on Radiant Heating System
The reason they have that "bypass" in there is because the system is piped wrong and it would deadhead the boiler without a bypass. For starters, the Taco circ in question is mounted wrong and may very well be at the end of its life because of this (hence why the lower two have already been replaced), causing your lack of flow. There really isn't a good way to purge air from that zone without cutting in purge valves like are present on the other two zones (likely done when the circs were replaced for the same reason).
Frankly, the best would be to cut the whole thing out and start over with correct piping and one central purge station. That's not likely to be in the desired budget, so the cheap and simple option is to verify operation of that Taco and then either reorient or replace it, as well as add purge valves like are on the other two zones.
GroundUp
Re: Boiler pressure constantly rises to/past 30psi relief valve trigger
The 10 degree difference between the aquastat setting and the gauge is close enough. If you wanted to make a science project out of it, you could wrap some black electrical tape around the supply pipe where it comes out of the boiler, and shoot the black tape with a cheap IR thermometer to see what the actual supply water temp is, but it's likely close enough to the 165-175 range to not worry about.
There's no magic in the standard 180 degree limit. It simply gives adequate margin against boiling the water inside the boiler. But as you've learned, the higher your high limit, the higher your max pressure. So if you want to keep your pressure low, try keeping the aquastat setting where it is at 165 and live with it for a while. If it heats the house adequately, there's no reason to raise it. The only reason you'd need it higher is if you don't have enough baseboard radiator length to heat the house during super-cold weather, which means you'd need higher water temperature to get a higher BTU/hr output from the baseboards.
Then as long as your max pressure stays around 23, that's probably enough margin that you don't need to worry about upsizing the tank.
jesmed1
Re: Residential Steam Boiler Replacement - EDR Questions
I looked here and found one that was very close:
Use the 4-tube Corto chart. Their version is 32 inches tall and 35 square feet. ISTR that the National Aero rads that were 30 inches tall had the same EDR as the 32-inch Cortos.
Re: Residential Steam Boiler Replacement - EDR Questions
No, there is already a 33% built-in "markup" for piping which is already too much.
Re: What boiler service tools do you carry with you?
But @EdTheHeaterMan , It's fun nonsense 😏
Yours, Larry
Re: Residential Steam Boiler Replacement - EDR Questions
Number 3 and number five are instant disqualifications. Boiler must be skimmed, and the only correct way to size the boiler is by measuring radiators.
Personally, I am not a big fan of king valves. Just one more thing to go wrong. Rather than coming up with all sorts of creative means to pressure bomb the sludge out of the boiler, it is preferable and possible to avoid the sludge in the first place.
Re: Residential Steam Boiler Replacement - EDR Questions
Definitely a good idea to have the chimney inspected and lined if necessary. And to have a chimney Cap added if necessary. But typically that's not the job of the boiler company. Will typically be done as a separate job by a chimney company
Re: Residential Steam Boiler Replacement - EDR Questions
And just to back up a bit. Are you certain that the boiler is actually leaking? Easy way to check is to fill the boiler above the top of the boiler, and see if any water comes leaking down onto the burners