Update + questions

1Matthias

So, after cleaning our boiler, installing proper main venting (The Big Mouth from Barnes and Jones is amazing, can't recommend it enough!), and balancing the radiator vents, our system now heats beautifully with no water hammer at all. However, I do have several questions.
1. In reading through some of the posts on here, it seems to be recommended that the thermostat be set to a cycles-per-hour setting of "1". When we tried this, the boiler ran for an exceedingly long time and completely overshot the set point. We now have it set to "3". Is this acceptable?
2. One of the radiator valves is leaking from the stem. We have tried stem packing, but it is still dripping. Can anyone recommend a good replacement? It is a 1-1/4" valve with no apparent markings. (I can take photos if needed.) The valve available on supplyhouse.com appears to be much shorter than the one currently installed, so that may make replacement difficult.
3. When we re-insulate the mains, could we use regular fiberglass batts and duct tape for the crawlspace sections? Per foot, that will be much less expensive than formed fiberglass, and as it is a crawlspace, aesthetics is not a concern.
4. We are considering adding a radiator to a room that does not have one when we re-pipe the boiler. What factors should be taken into consideration for this? The boiler is exceedingly oversize, so boiler capacity is not a concern.

Thank you!

Fred

- What kind of thermostat is it? 3 CPH is fine but it will cause the boiler to cycle on and off a little more. Probably will even out the temp swings though. Not sure why 1 CPH would cause the boiler to run any longer than necessary for the thermostat to reach set point. I can understand if the temp went up a degree or so after shut down just due to the mass of the radiators.
- Did you put enough packing around that valve stem and tighten it up snug? You can replace the vale but that will also mean replacing the spud that goes into the radiator. It is a little more difficult and if you can avoid that, I'd do so until after the heating season. You may also have to add or change out the vertical nipple to get the height you need. Depending on how much difference in height, you may be able to use an extender but you want to ,make sure you keep the pitch on the horizontal line.
- You can wrap the pipe with batting but that is messy and the cost of pipe insulation isn't so expensive that it is worth the trade off. Like I said, batt material is ok, certainly better than nothing.
- For an additional radiator, make sure you use steel pipe, not copper, make sure you have good pitch back to the main on the new piping and make sure you size the pipe large enough for the radiator you intend to install. Make sure you get a steam valve and not a hot water valve or a cheap knock-off from China. Try to Tee off of the main at a 45 degree angle.

the_donut

1. What kind of thermostat do you have? Some have a correction for undershooting and overshooting.
2. Clamp down on packing nut and if system is one pipe fully opening will help seat.
3. Depends on what your time is worth. Using preformed stuff is quicker, looks nicer and usually insulates better unless you are good about sealing with tape (that is a lot of wrapping).
4. As long as the riser can handle the edr of the radiator, it’s pitched right, piped in steel, and vented properly, should work fine. Do a heatloss calc of room and place near low surface temp area like window for comfort. Consider gains from nearby heat sources including rooms under floor.

EBEBRATT-Ed

1 cph will overshoot. If you change that valve search for different brands and you should be able to find something that will be a near match. I agree with @Fred on the insulation.

Make sure you size the steam pipe to match the EDR of your new radiator

1Matthias

1. It is a Honneywell TH3110D. Seems to not have too much in terms of options, but it's what we have.
2. I cranked down on the packing nut already, as well as backing the valve stem out as far as possible. The packing material was graphite impregnated rope, and I used about 4 wraps worth. I've attached a photo of the valve in question. And yes, this is one-pipe steam. @Fred That's what I'm kind of afraid of, is having to replace either the vertical nipple and/or the spud. Considering how old the pipes are, that's a can of rattlesnakes I don't want to open at the moment.
3. If the main disadvantage is having to spend more time working on it, that's not too much of a problem.
4. Ok. It would be for a bathroom that is currently unheated, and appears to have never been, despite there being a Tee in the main roughly where the takeoff would have been. We are looking at 1" pipe for the riser, with a very small (<20 EDR, probably closer to 15) radiator. I've done a (very) rough heatloss for the one unheated wall, which came to about 2400BTU/H.

Thank you!

nicholas bonham-carter

I would get the pressure down well below 1 psi to maybe 4 ounces, and see if the valve stem stops leaking. You will have a bit more short cycling.—NBC

Fred

Try a couple more wraps of the packing and snug up the packing nut but not so tight that you crack it.
A 1" supply pipe will support up to about 25 EDR so if you stay at or below that, you should be fine. Just make sure you have good pitch on the horizontal pipe.

1Matthias

@Fred The extra packing seems to have done it. It leaked black sludge (Probably graphite off of the packing) for an hour or two, and now seems to have stopped leaking at all.
@nicholas bonham-carter Not really an option with the controls we currently have, but that may change after we re-do the piping etc this summer.

Fred

@1Matthias , Great! Packing Probably just needed to swell a bit.