This is our second season with our Heatmor 200 CSS. We installed it in somewhat of a hurry last year after abandoning the propane that was costing an obscene amount of money. When I say obscene, I mean that one year of propane paid for the furnace itself. I suspect that got your attention.
The house is early 1900's, 10.5 ft ceilings, just under 3,000 square feet, two huge fireplaces (I keep chimney balloons in them 99% of the time to minimize heat loss) and a mixed bag on insulation. Our twenty-seven, seven foot high windows are modern replacements that are quite efficient, but our insulation is older blown stuff in the attic and we have balloon walls. We have huge cast iron radiators that were steam when we had the propane boiler, but are also water-capable. So we switched to circulated hot water to accommodate the Heatmor and retired the propane furnace entirely last year.
Our original installers last fall did a horrible job (this is not a Heatmor or dealer problem - they were a clueless couple of private HVAC guys I stupidly hired that took us for a ride). This included everything from putting our pumps on backwards to providing almost NO support to the tens of feet of 1.25" black iron pipe in the basement that tie into our radiator system. They just suspended the new pipes on top of the old, pre-existing pipes of the radiator system, etc. I am amazed I was never awoken in the night to the sound of rending metal as hundreds of pounds of water-filled pipe tore off the basement ceiling.
A tremendously capable builder/renovator friend of mine came to our rescue and redid the furnace-side plumbing. We weren't in a position to address the basement plumbing mess at that point. That got us up and running the weekend of Thanksgiving last year and we finally had heat (after a solid month of using electric space heaters in key rooms and the rest of the house in the 50's).
Our biggest problem last season was that the original design had the two thermostat-called circulator pumps running the water directly through the radiators and back to the furnace. When the cycle would start, the impact on the furnace was massive with all of that room-temperature water from over a dozen radiators dumping into the furnace. The needle on the furnace gauge easily dropped 70 degrees and a huge burn cycle would start.
Worst of all, we had water level and pressure problems. In a nutshell, I think the water in the radiators - sitting several feet above the level of the furnace (which is a good 70 feet from the house), would rush "downhill" to equalize. If you topped off the furnace, this situation caused it to push water out of the Heatmor's overflow pipe on the top repeatedly after the pumps would stop. Once it "balanced out" to the point that it wasn't forcing water from the top, I think the end result was less water in the Heatmor than it should have had. This led to overtemps during the burn cycle followed, of course, by huge drops in heat when the system was called and all that cool water came rushing in again. Radiators, of course, also require periodic bleeding to get air out, etc., that undoubtedly added to the furnace-side hassles.
We made it through the season, though, with a warm house but a lot of wood cutting and loading. Still, we spent less on wood for the whole season than a single month of propane AND we had endless hot water in the showers. Our electric bill was cut in half from the hot water heater savings. Wood was a mixture of stuff: a huge Ash tree we had taken down late in the summer (it was dead in the top and threatening the house) and various loads I bought from some local suppliers. Some of the wood I bought was large, minimally split hardwood that was heavy, but loaded decently. In January, I had a logging truck delivery of 16-18ft hardwood in 10-14" diameters that I sawed up on my own - by far the most cost-effective source dollar-wise, but not effort-wise. I cut it into short rounds based on what I could reasonably lift... but cramming those in the furnace was a bit of a workout and not something the wife was going to comfortably be doing. I have no gripes about the exercise, but I'm a programmer/network admin who gets his cardio workouts on a bike... so this seasonal amateur logging operation is likely a future back injury in the making.
We decided to correct the major problems this fall before the season started. We split the furnace and house into two separate circuits. The two feeds from our furnace cycle through two new heat exchangers in the basement. This puts the furnace on a much smaller capacity loop that never touches the radiators directly. Furnace water levels have been perfect since doing this. The donut-shaped bladder in the Heatmor always has water and a varying amount of pressure in it depending on the water temperature (hot and idle vs. initial start of a cycle).
The other side of the exchangers is a closed loop of just the radiators with a couple of small expansion tanks (which I don't know were even really necessary) and another pair of circulator pumps. We initially tried running the furnace pumps 24/7, but that failed miserably. Turns out that the constantly cycling hot water from the furnace transferring heat across the exchangers to the house loop caused the hot water to rise into the radiators, drawing cool water behind it that kept the furnace going almost constantly. The house kept getting hotter and hotter - a good five degrees beyond the cutoff on the thermostat - and the burning outside was nearly constant. So we switched to having the thermostat turn on all four pumps when it calls for heat. When it satisfies, all the pumps stop and the furnace is free to heat itself back to idle until the house calls for it again.
All of the plumbing in the basement was also redone. The miles of black iron pipe are now insulated and properly hung with pipe hangers so strong that you can literally do pull-ups on them. No more new pipe draped every which way over the older pipes. It looks like a professional HVAC facility in our basement (both in scale and quality of the work). My same perfectionist friend that saved us last year was hired to do this and it took the two of us a solid week to do it right. The results could not be more of an improvement. I will post some photos if people are interested.
Last season I also set the thermostat on a day/evening/night schedule with the usual higher and lower temps in an attempt to be efficient. I think, honestly, that those multi-degree drops put even more stress on the furnace and the burn cycles. I could be wrong, though. This season I've just set the thermostat on a comfortable temperature and left it 24/7. When the thermostat loses one degree, it calls for heat and, on average, I don't think I hear the pumps run for more than about 3- 5 minutes before the house is satisfied. The furnace burns for a while beyond the end of the cycle, of course, and gets back to idle. Mix and repeat. The colder it is, the more often we have these cycles - but they are all quite short from the thermostat's perspective.
So, if you're still alive after reading all of the crap above, here are some questions I have:
1) I'm interested in any general opinions on our old (direct) vs. new (exchanger) configuration and whether it sounds like we did it right. I feel like the system is running more efficiently this way and, above all, feel it's going to be easier to maintain by having the house and furnace on separate loops.
2) Am I wrong in assuming that the constant temperature approach is, in this particular system, a better approach? Or should I be doing the usual day/evening/night cycles with the thermostat? Technically, it should be day/night since someone is almost always home making sleeping hours the only time we might tolerate it being much cooler. The house is MUCH more comfortable and constant this way, too. The radiators tend to stay at least warm to the touch most of the time and never seem to need to be piping hot.
3) Related to question #2: are the short burn cycles of this constant setting preferable to the long, harder burns that come from a 2 or more degree drop in the house and re-heating cool-to-the-touch radiators?
4) I know this is talked about a lot elsewhere, but I'm very curious about wood sizes, etc., in relation of the above questions. Until I get more into gathering and stockpiling my own wood during the year, I am buying loads of various kinds. Most suppliers around here bring seasoned, split, indoor-wood-stove-sized oak. This stuff almost feels like kindling to me compared to the massive logs of last year - but it's seriously easy to load (wife-friendly!) and does burn hot as hell. Yes, a load of it does burn down to just coals over the course of a 20-degree night. But is this smaller, easier-to-load and hot-burning wood a good fit to these shorter cycle burns, or am I better off going back to the heavier rounds? Whatever the case, the guy who brought my current load of comically small 18" split oak toothpicks is going to bring me 24" lengths with fewer splits (more halves, some smaller wholes and quartering only the largest pieces). I'm hoping this will be a nice compromise between burning time/efficiency and preventing my first back injury.
Thoughts?
5) What IS the proper moisture level I should be looking for in the wood sizes I'm talking about? I have a moisture meter that shows me between 20% - 30% on randomly sampled pieces in this most recent delivery. Are moisture meter measurements pretty consistent and reliable across devices? The Heatmor manual cites precisely this range, but I want to know that my meter's reading is consistent with their means of measuring. Granted, the Heatmor manual has a tendency to piss me off with its ability to confuse, contradict itself and completely not address other questions I tend to have.
My moisture meter:
http://www.amazon.com/General-Tools-MMD4E-Digital-Moisture/dp/B00275F5O2/ref=sr_1_1?ie=UTF8&qid=1323624785&sr=8-1.
I'm sorry for the length of this message, but I wanted to tell a full story. I have a lot more questions and any replies I get will likely spur more. I also realize that the reality of what is "right" in the details is what works best for the owner. Is my house warm? Yes. Am I comfortable with how often I load it and how much effort or cost I put into obtaining and loading the furnace? While everyone will find their own comfort level, I want to be sure I'm being at least being sensible on the bigger issues. Input from the experienced and helpful OWB owners on this forum has always been appreciated!
Thanks!
- Aaron
Sweet Briar, Va
Author
Topic: LONG saga and related questions: plumbing, wood sizes and burn cycles (Read 4222 times)