With the cold snap that we have had in the northeast recently, heating systems have been put to the test. I live in a neighborhood where the housing is first generation energy efficient homes built in the late 70s. The heating is hotwater baseboard but the strange thing about these systems is that they ran 1/2 pipe from the boiler to the baseboard heat. My second floor has difficulty staying up to temperature when it is extremely cold and I’m wondering if the reduced flow caused by the 1/2″ pipe is the cause. If I were to replace as much of the 1/2 as possible with 3/4 inch, would this cure the problem? I would replace it all, but there are places where I would have to do excessive demo in order to get at the copper.
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Replies
How is your hot water heated? we had electric hot water, and one of the elements burned out in the boiler (no, not really a boiler, since it didn't create steam), and on cold days the system couldn't keep up.
This system is oil fired hotwater baseboard.
Minor comment: Are the basebooard fins clean? They get coated with dust whiich reduces their ability to transfer heat.
Yes, the fins are clean. I've done extensive remodeling to this house and as I've finished each room I've vacuumed the fins.
In your remodeling what did you change?
Are walls moved so as to change the way heat moves in the house?
Are windows as good or better than they were?
Smae Question re insulation?.
Excellence is its own reward!
In this house I haven't moved any partitions. Renovations have been limited to new rock, trim some electrical etc. I also added central AC which I have insulated really well. I believe that this problem was there even before any of these renovations. Thanks.
Jack
The central A/C may be a contributor to the problem. Remember that there are two key factors to keeping heat in your house - insulation and minimizing air leaks. My central air system (professionally installed when the house was built) is insulated but leaks like a seive. This means that every air register in the house acts as a vacuum for warm air during the winter time unless you cover them up.
More generally, you might want to see what leaks you can close up. Common offenders would be recessed lighting, attic fans/stairways, old windows/doors, and ceiling fixtures.
Just a reminder to the folks who are talking about this like it's a 50-year occurrence. In New England, it's not. This is just a normal cold snap. The local paper showed that this particular cold snap doesn't even rank over the last 30 years.
Pete
Brad:
Thanks for the suggestion. I did the central air install and really took pain staking efforts to insulate well. Even so, I have noticed that the hot air definitely wants to travel towards those openings which happen to be in the ceiling.
Yup. Any opening in the system (and there are bound to be some; around the filter is a good one or small gaps at junctions) will turn your A/C into a chimney. It's deceiving too because the registers may not feel cold because warm air is moving through them.
You might want to try covering some up and see how much it helps. An easy method is to get one of those stick-on plastic window kits (comes with a sheet of clear heat-shrink plastic and some peelable double sided tape). They're available everywhere. Longer term, you can get covers to fit. Around here, the power company sells them in its energy saving catalog.
Pete
Brad:
I've seen magnetic covers for these vents. I think that I might give them a try. I am still very tempted to swap out some of the 1/2' pipe in hopes of increasing the volume of hot water and therefore having more of a shot at getting hotter water to the baseboards themselves.
Lots of great comments. You also say that you can use space heaters or add clothes.
Here ,you would be a canidate for a wood stove or a gas stove that looks like a wood stove. Both are very effective and enjoyable.
Heat pumps are often matched with one of these units. Running heat strips is not popular.
Tim Mooney
Seems to me that, given the extreme and rare temperatures, you may just be exceeding the design rating of the system. Systems are designed to meet the needs of normal temperature with a margin added for the low end of normal. If the system was designed for very rare cases it would be massively over designed and inefficient for the other 99.9% of the time.
The solution is to modify your behavior, expectations and to make temporary changes to get you through the tough spot. Moving into interior spaces and closing or adjusting valves to abandoned rooms will allow the heat to be concentrated in a smaller area. Just make sure these rooms stay slightly above freezing to avoid damage. Temporary storm windows, 4mil plastic stapled or taped over windows, are cheap and easy to install and add a substantial increase in insulation.
I live in Florida and we are seeing temperature in the teens. Some people think that the inability of their heating to keep the entire house in a clothing optional range is a design flaw. In these parts this weather is being referred to as a 50 or 100 year low. Many of these people need to adopt an emergency mind set, put on a sweat suit or get friendly under a comforter.
The temps we're seeing now are ones we do see, they are not out of real whack, like seeing 10 degrees in Maime. It is just we haven't seen them in awhile, warmer winters,bobl Volo Non Voleo Joe's cheat sheet
I'm with you on this as the likeliest answer. Heating systems are designed with a temperature in mind. Your (the original poster) house loses x btu/h at 25 deg, y btu/h at 10 deg, and z btu/h at -5 deg, and z > y > x. So what is your heating system designed for? Mine is designed for the 15 degree temps that account for our weather 97% of the time. That means that 3% of the time the heating system won't quite keep up, and we wear sweaters. Should I have installed a heating system capable of handling sustained -30 temps that are theoretically possible here, or the -10 temps we might get once every 10 years, or the 0 temps we might get one night in 5 years, or???? I could have, but the cost would have been a lot higher. One or two days of wearing sweaters and stoking the fire versus thousands of $$$ for a system that covers all possible temps but is largely unused? It's really a risk-reward game of paying for a system that can produce X btu/h, against temps that cause the house to lose btu/h at some greater rate.
I don't know the offical design temperature for my house but it seems to be around 25F. Anything lower and the heat can't quite keep up. No big problem. I have a couple of small space heaters. Either, with the central unit going, will keep my office toasty and the rest of the house at about 50F. Electric, propane and kerosene. The propane and kerosene are for when the power goes out. Be impared.
The cost of an oversized heater, or air conditioner, is not only the purchase price. Under normal conditions they run, excepting the more sophisticated variable speed and output models (big $), less efficiently outside their design range. An oversized AC unit won't run long enough to remove the moisture and can leave the house damp, stuffy and clammy. An oversized heating unit will cycle excessively.
That's all consistent with what I've come to understand. I don't have the sense that it's common knowledge among homeowners though. I think the expectation is that A) it's cold, B) I turn up the heat, C) it's warm, without regard to sizing the system and the cost implications of doing so.
Doesn't it seem easier for an HVAC contractor to oversize a system so that he doesn't get complaints about not enough heat/cool, rather than get into the subtlties of proper sizing means better humidity control, etc? (Didn't say it was right, just easier.)
you could check the inlet temperature & outlet temperature from that loop or register, the typical inlet for space heating would be 170-200F and the oulet should be about 20 degrees less at normal flow rates.
the pipe size dont mean much, alot of jobs used 1/2 for service piping and if it is designed right it is OK.
all things considered you might consider a high head circulator pump if you have a lot of small bore service piping , especially if there is tube & fin convectors, box type radiators as heating equipment through the house..
anyway good luck
TS
I live and build in North Idaho. We are no strangers to an occasional cold snap. I recently built myself a 3200 sq ft home with hydronic heat on the ground floor and hw baseboard on the second floor. My plumbing/heating contractor installed in line pumps (Grundfos) to both systems and they work great! Our house is a comfortable temp throughout, no difference room to room,and no fluctuation. What I'm getting at is;with the half inch supply,and the extreme cold maybe your cooling off before you ever get to your baseboards,due to your restricted flow. This is just a shot in the dark,but you may want to look into an in line pump installed in your mechanical room. It would certainly be alot less work than all that demo to change to three quarter inch pipe. I did the wood stove thing for years,and you can't beat wood heat. Have you ever cut 10 cords of wood? Where on your property can you store it? Do you have a truck to haul it,a place to cut it,and the time to do so? I don't think that there is aperson in the world that could deny that wood heat does not bring a certain atmosphere to a home.( I still frequently put them in the homes I build.) They also can't deny the dust created in the air,the bugs in the wood,the dirt made by transporting the wood inside, and the ever present danger of a possible chimney fire.
Edited 1/29/2003 11:16:11 AM ET by barnesy
I recently dealt with a similar problem, and was happy with the result.
Installed HW baseboard, good system, but the house just never warmed up when the really cold weather set in.
It's an old place, masonry walls, no insulation anywhere, so no surprise there.
The temp in the room was always about 15 degrees behing the thermostat setting, and that poor Teldyne boiler could run nonstop.
Insulated the roof to R-40, the house is now comfortable, and the system has no trouble keeping up. My guess is the insulation will pay for iteslf this year.
Moral of the story: If the system seems to be designed appropriately, any thermal control you introduce can only help. Start with the top of the house, work your way down.
DRC
The more that I consider the draft that I am getting from the AC vent, the more that I think your reasoning is right on. The attic insulation is really quite good, but I have determined that there is a definite draft coming through all of the AC openings. There is a heat exchanger in the attic which is insulated, but, I think I need to do some more work there. Thanks!