Best Of
Re: Pump Size
You'll never get 1 GPM through a 250ft loop of 1/2" PEX with a standard sized circulator. Usually .8 per loop is about the best you're going to see, but .6 is more realistic especially if the fluid is cool. Would I be correct in assuming you don't have primary/secondary piping and are trying to use a tankless water heater as a space heating appliance? If that's the case, that's your problem as tankless WH have a tremendous amount of resistance to flow. Also, like Bob said above, your heat load is almost certainly far lower than calculated.
GroundUp
Re: Please comment on a boiler re-install
Really! This looks like a DIY'er trying and terribly.
There seems to be a supply and return where the black iron and pex? connect.
Rip out the orange stuff and run air or water to each perceived Zone . Trace it that way and then see what happens.
I have seen worse. (However, I can't remember where). This can be salvaged but it would be at a cost of time and material including callbacks.
Intplm.
Re: Low water cutoff question
sounds like a salesman more then a tech.
get a second opinion.
pecmsg
Re: Please comment on a boiler re-install
My sympathies………and the reason I do most of all electrical and plumbing myself.
I do have skepticism with any legal approach to a "shoddy" installation. You, as a homeowner, are up against a professional. You don't have standing against a professional in just about every case. Now, if you can drag another professional into court with you, now you have the POSSIBILITY of prevailing. Even in that situation, it's one professional against the other. How likely is that to occur?
LRCCBJ
Re: Asking for advice for combi boiler replacement and hydronic system upgrades
But you don't need closely spaced Ts in the primary — boiler — loop at the boiler, just where the secondary loops attach. The first of your two sketches is correct.
Re: Understanding Steam Boiler Start Up Logic
You kind of answered that yourself. The pressuretrol (or vapourstat) is on, allowing the boiler to fire, at any pressure less than the cutin pressure — so when the boiler is cold and the gauge pressure is zero, the control is on and the boiler will fire (all other safeties OK).
As the pressure rises eventually, in most systems, it will reach the set cutout pressure, at which point the control opens and the boiler stops firing. As the pressure drops, it will reach the cutin pressure (you set the amount of drop with the differential) and the control closes again and off you go.
No bypass is necessary — the control is aways on below the cutin pressure.
Re: Cold 2nd & 3rd Floor Radiators
You need vents on the ends of the main and the vents on the radiators checked. The boiler piping is questionable both in size and material but I think venting is your main issue.
In the laundry room it looks like a 3/4" pipe ?? coming off the top of tee where the vent should be. Maybe there is a vent up behind the ceiling. I would check that pipe out and see where it goes if you can. I may be tough to get a vent at the end of the main but it can also be drilled and tapped. I think that is the most important thing to do.
Also check the water level while it is steaming it should be steady or moving slowly up and down an inch or so. Violent fluctuations are not good.
Also what pressure are you running at? Should be 2 psi or less.
The Copper return line dropping out of the tee in the laundry room behind the washer/dryer….how does that get back to the boiler? Must be a wet return.
Re: Vertical Radiators
I'd drop a pm to @Nick_Castrads here. Sometimes those steel rads don't work well with one pipe.(no vent provision) But he'll set you up.
Re: Please comment on a boiler re-install
Not necessarily. People might pay a "standard rate" and their decision was simply based on the salesmanship of the contractor. I have observed that people make decisions on how a person speaks and how convincing they are. The actual capability of the individual is impossible for any homeowner to vet unless they have photos of prior installs (usually never happens) and know what they are looking at. It's no different than you and I picking a surgeon.
LRCCBJ