In fairness to all, we don't discuss pricing on the Wall. Thanks for your cooperation.
I said I would post about the new control method I ran the second half of the season from January on. For those interested read on.
First, a reminder that it is my position that these systems originally with coal fired boilers were designed with significant extra radiation and boiler capacity. It is my contention that were it not that way, no ongoing continuous control of the output would have been possible. So even on design day, these systems will heat the house with partially full radiators. It clearly is that way in my house.
Anyway, I set about trying to run my system that same way, partially filled, experimenting with a lot of things over many years now. Partially filled radiators border on slight vacuum conditions inside them even with a big boiler firing. That is why next to no pressure at all at the header is required to keep radiators partially full. Actual pressure does not build until radiators actually start to fill completely - something that is never required to heat the house. So the project becomes how to control the boiler such that radiators are only partially full over as long periods as possible - which evens out the heat as much as possible.
I have also discussed the use of vacuum and its truly magical ability to even out the heat. I won't detail it here again. The control I ran this season used a combination of a heat sensor and a pressure(vacuum) sensor to cycle the boiler whenever the tstat was calling for heat in a way that kept rads partially full, and also adjusted the percent on vs wait of the cycles automatically without a PLC according to the conditions outside. It was easily the most comfortable heat yet, the numbers showing perhaps another 5% improvement on consumption beyond what I have already achieved. Given the reluctance of so many to give even a simple PLC a try (a shame because they really are easy to learn), this control does not require one. I did run it with my PLC doing the simple connections between these components so I could collect data, but one is not required.
This control would be installed in the control wire from the tstat to the burner and easily bypassed with one switch that could put you right back to the original vaporstat control just as it was. I installed a temperature switch at the supply pipe of my most remote radiator (in the garage) and the ultra low pressure switch at the outlet of that same radiator going into the dry return where my single vent/check valve is also installed. In the boiler room also wired with the above components is a delay off timer. Whenever the tstat is calling for heat it runs the boiler until both there is steam at the inlet to that radiator AND no vacuum PLUS 2 minutes on the adjustable delay off timer. I left it that way for 3-4 months and didn't touch a thing. On an actual cold start there is no vacuum so it runs until steam hits that far rad + 2 minutes to get a partial fill. When the system is already hot, new steam hits the radiator inlet well before vacuum is gone so the run is to no vacuum + 2 minutes. The trigger for each new burn is the inlet temperature switch dropping below 180F or so signalling that all the forward steam motion from the last burn in the vacuum has completed. So during a call for heat I just oscillated that way, starting each burn when the rads just started to actually cool and burning until all the vacuum was gone plus a small amount.
So how was this self-adjusting to the conditions? To me, this is the interesting part. First, one of the magical things about running in natural vacuum is that at the instant all the vacuum is gone each time you burn, you have just returned each and every radiator back to exactly the same fill amount it had when the burner went off the previous cycle. So, once you have a partial fill, it is very easy to maintain it with vacuum. The self adjusting part comes from the fact that the percent burn vs wait of these cycles changed a lot with the conditions all on their own. In the cold why of course the steam is condensing at a faster rate. This means that the time from when the burner last shutoff to the trigger from the temperature switch is shorter. The vacuum that got pulled in the system is slightly deeper for the same wait time because more steam is condensing per unit time so the burns must get slightly longer to kill the vacuum. When you think about it, it really doesn't take a big swing in these things to change the burn % of the total cycle time a lot. I have said all along that there is something natural and a sweet spot at around 3cph. This control operated that way all on its own - I did nothing to control the length of these cycles. I just let the steam do its thing. The temperature switch fired the boiler and the vacuum switch told me when I was partially filled back up to the same spot I was before(plus a little). So in mild weather I would get say 5-6 minute burns and 15-16 minute waits. In colder weather they would be 8-9 minute burns and 11-12 minute waits. During calls for heat this is roughly a 25% mild day burn rate each cycle and 40% in colder weather. In milder weather the time from call to satisfaction was shorter than in colder weather. Reducing the 2 minute timer would extend that time in all conditions. The longer that time is from call to satisfaction, the more even the heat is by definition. I have never required greater than 50% burn rate even at -20F to heat the place with my big boiler.
I will note here that the 2 minutes additional time is arbitrary and easily adjustable. It is needed only to overcome leaks and push that small amount of air back out each time so you don't lose ground. The longer you make that time, the more your system becomes just like a pressure one - if you make it long enough you will fill your rads and pressure controls will take over. I just chose that number and never touched it for 3 months. I think one minute would have done fine. It is not critical. It just has to be enough that over enough cycles the system will gradually fill as opposed to emptying out due to air leaks. The leak rate is not related to the conditions. Need to recover from a power outage or something? No problem, throw the bypass switch.
So to sum up this control requires 4 components on a 2 pipe system: the temperature switch, the pressure switch, the check valve, and the delay off timer. These things don't total $200. It is pretty simple and easily bypassed. It is worth the effort? I already know the opinion of many here is no. All I can say for those interested is that the comfort level is dramatically better than my vented vaporstat system and overall efficiency improved 30% or so from that same system.
Looking for some small radiators for 12' x 12' bedrooms as well as how to install them here in Vermont. New hot water boiler.
I have been twice to HTP. The UFT heat exchanger comes from Korea and the boiler is assembled at the plant. The EFT has a Polish heat exchanger. All the S/S tanks are assembled in the plant. HTP is the second largest consumer of S/S after the US navy. From looking at a similar situation here, I would say that it is water hammer that is the cause.
Separate heating and cooling systems.
Where are you located? e.g., how many days per year do you need heat, and how many days per year do you need cooling? For example, I live in western Mass, and need heat about 220 days per year, but only need cooling about 30 days per year. Therefore, I have much, much more invested in my heating system than my cooling system. I have a modcon boiler, ~130 feet of high output baseboard in my 2K sq.ft. split, in 3 zones. I use two, 8K BTU window shakers for cooling.
I want to thank you for putting this up for us, and everyone who is here to support us. It is very humbling for me. This is a great community to be involved with, and makes this even more special since I have only met four people off this site.
It looks like we will be 4-8 months doing this, so will be long road. Luckily, both of us are stubborn and don’t give up easily, and we have great attitudes. It will be a new journey, but we are up for it.
Thanks for everything.
Rick and Tanya
Firing up once a month to dry things out on the fire side is a pain? Say what? Do you have or can install a seven day programmable thermostat? If you're concerned, set that thermostat to fire the system once a week for half an hour and then forget the whole problem. Set it to run while you are in church, or out golfing,, or whatever.