Steam to the inlet valve of all radiators at same time?

ethicalpaul

KC_Jones said:

What is your main venting like? This sounds like a main venting issue. All radiators should be getting steam to the inlet valve at around the same time, in the whole house.

It all starts with the main venting in the basement.

This quote from KC in another thread really caught my interest so I thought I'd ask about it. My 2nd floor radiators all have their risers in the exterior walls, and those pipes get COLD (I can feel the cold air flowing down into the basement around them). The first floor radiators have no pipe in the exterior walls, and a couple of them are on the interior of the floor layout, which keeps their supply lines toasty.

In watching my boiler do its thing, I know it takes a long time (many minutes) for the steam to heat its way up those cold pipes to upstairs, so no matter how good my main vent is, how can I expect steam to arrive at all the radiators at the same time? Don't I need to rely on varying vent sizes at the radiators to slow down the steam at the radiators with short, warm runs?

Thanks! and thanks especially to KC for all the help provided to so many and this possibly annoying question!

KC_Jones

The situation you describe is what most of us have, though my pipes and within the conditioned space. I still have at minimum 9' of extra pipe on my second floor Rads.

You are correct you will need to manipulate the rad vents for this portion of the balancing. The batter way to state it is steam fills the mains first before any rads get steam.

It all depends on room temp, rad size, distance from boiler. For example in my house the smallest rad is furthest from the boiler has the largest vent. My biggest second floor rad in our bedroom has the smallest vent. This keep it slightly cooler like we want for sleeping.

If you need it to the second floor quicker go one size bigger, but you need to start with some kind of baseline, for me that was the same size vents (inherited with house) on every rad. I knew this didn't work, but it gave me an idea of which one to make bigger and which ones smaller. I recommend changing one at a time and living with it like this. As a change either way can affect the whole system.

ethicalpaul

That is awesome, thanks! I thought of something else that’s making my situation more difficult, and that’s the fact that on my bedroom radiator I have that pitch problem discussed in the other thread where a 1” pipe definitely has some water resting at the bottom of it all the time which is probably wrecking a lot of steam.

I’ve raised it up 1.5 inches so far which has stopped the loud hammer, but there is still a much quieter gurgling and I know that’s bad for the steam.

I’m 90% decided that I’m going to rerun that riser inside the living space

Thanks again, and your furnace install pics are amazing bordering on insane! 👏🏻

mikeg2015

More importantly, do you want that to occur? Keep in mind that no house is perfectly balanced in all weather. As it gets colder outside or wind increases, air leaks increase and stack effect increases. So in my house, if i get things perfectly balanced when it’s 30F out, I find that at 10F I need more heat downstairs, and upstairs is overheated. In mild weather, the downstairs overheats, upstairs is cool. Fortunately, the heat pump does a good job upstairs until 37F outside and downstairs I let het heat pump run until 15F to help balance it. Both thermostats are wired in parallel to the boiler to call for heat as backup. I don’t like the cold defrost air upstairs, so don’t use it below 37F outside to keep it out of defrost in most all weather.

That being said, upstairs vents are slightly larger than downstairs due to the volume of the long riser.

ethicalpaul

Yep I hear you. Interesingly my system has kept all of the house pretty comfy all the time even when it had everything wrong.

I’m futzing with it mostly because it’s fun to learn and do. My plan is to replace the boiler myself in a couple years