Uneven heat, plus cycling

Josh_16

thanks for all of the thoughful help. Someone on Brownstoner also suggested that maybe my main vent isn't big enough.

As to the comment about boiler size and my needs being affected by the renovation, I don't think I need to lok at relocated walls. We put insulation into two exterior walls plus new framing, plywood, Tyvek and hardiplank(front and back exposures) plus the ceiling, where there was none before(this is a 140 year old brick and frame). So we are retaining a lot more heat than the house used to retain before we bought it.

I have not done the analysis for boiler size yet, but if my boiler is too big, are there adjustments I can make as alternatives to replacing it? I'm just tapped out right now.

Thanks again for your thoughtful comments and for taking the time.

Josh_16

Uneven heat, plus cycling

Folks on Brownstoner referred me here. I am a homeowner and I posted the following there:

Boiler -- Who's right, plumber A or B
Help me figure out which plumber has correctly identified the problem. We have a 4-story, 2-family house on a single zone old fashioned steam radiator system. The boiler is not brand new but not ancient. House was unused for several years before we renovated, and not well maintained in the years before that. The problem is that the bottom floor runs about 8-10 degrees cooler than the rest of the house (thermostat is upstairs). Bottom floor has low ceilings, insulation, and no discernable drafts. This is not a problem of "heat rises." The problem is the room where the thermostat is located reaches temperature before the bottom floor has had a chance to heat up.

Plumber A says -- we need to clean the sludge out of inside the boiler (my guess is nothing like this has been done for years and years, but I don't know how necessary it is). According to plumber A, there must be a lot of sediment settled in the boiler which apparently causes the boiler to think the steam pressure has built up throughout the system before sufficient pressure reaches down to the lower floors. He says that, when the boiler is on, steam goes through the pipes to the top floors first and the pressure is supposed to build up from the top down until it reaches the requisite pressure to shut the boiler but in my case the boiler cycles off due to it thinking the pressure is all there before the steam pressure fully builds up on the lower floors. This seems credible because I have observed the boiler cycling on and off every 2-3 minutes while the thermostat is calling for heat, but I question the diagnosis because the radiators do get hot on the ground floor. Plumber A says I am wasting a lot of energy (and money) having the boiler cycle on and off and that cleaning the sediment out of the boiler will alleviate the problem.

Plumber B says none of what plumber A says matters. We should get new valves on the upstairs radiators to limit how much heat they put out so that the upstairs reaches the thermostat temp more slowly, giving the radiators downstairs time to heat up before the thermostat turns the system off. His solution seems like it may work but I dont' know if he is right that plumber A's diagnosis is irrelevant to the problem. Also, the solution seems wasteful; I don't want to run the heat longer, especially if Plumber A is right that I am wasting energy with the boiler cycling on and off. But if the cycling is, in fact, normal, or unrelated to my uneven heat distribution problem, I want to make sure I fix the problem.

Anyone have a sense of who's got the better diagnosis here?


Here's my follow-up to some comments I got back on Brownstoner:

If it helps, the boiler is in the cellar. The floor I am having trouble getting up to temperature is the basement (garden level apt). It makes sense to me and is my experience that the lower floors heat first, as the lower floors come into contact with the steam first. What plumber A is suggesting is that the pressure starts to build back towards the boiler from the top once the steam reaches the top as the boiler continues to send more steam.

Noel

Lower floors get steam first?

Steam is lighter than air, that's how it GETS to the top floor. This means that the steam fills the system from the top first, then down.

Guy "B" is on the right track, it's in the balancing of the air vent valves on the radiators.

Noel

Mike T., Swampeast MO

Problem is the basement, correct?

Do you have radiators in the basement?

Josh_16

more on plumber A vs. plumber B

Basement has radiators, it is a garden level apartment (in NYC we call any story with the floor below grade but more than ahlf the height above grade a basement; anything lower a cellar). The boiler is in the cellar, one story below the basement apartment, where, of course, no one lives and there are no radiators.

Folks on Brownstoner are advising me to do the balancing first; replace some of the valves. But the cycling still bothers me, especially if it is costing me in wasted energy and boiler wear and tear, but I don't know if it is connected to the uneven heat problem or whether it is conencted to any need to flush out "sludge".

Other facts -- system is relatively quiet, not a lot of banging, hissing is pretty soft (knock on wood). When we frist turned the system on in the fall, I got a lot of foggy, dusty steam in the house whenever the heat was on. That went away after a few weeks. Also, just to be clear, teh radiators in the ground floor apartment

Obviously, I could spend a lot of money doing everything, but (a) I don't have that kind of money and (b) I don't want to mess with what is working.

Thanks again for the help.

Noel

this might help

balancing

Glenn Sossin_2

I vote for

B. But there may be another cause. The radiation itself may be out of balance with the heatloss of the rooms there located in. You mentioned rennovation - were walls moved or added? Do you know if it ever heated properly? Did the rennovations include alot of new insulation and windows? This might be the cause of your increased cycle times - the boiler is too large.

While it's not the best way, take a look at two rooms, 1 from each floor, that are similar in size and characteristics - alot of windows, outside walls etc. Then compare the two radiators, is one significantly bigger than the other ? For similar rooms, the one on the top floor should be a little bigger than the one on the first floor - because the 2nd floor has a cold ceiling, while the 1st floor has heat above it. If there is a big difference, then you might want to have plumber B (since he seems to know more about whats going on) to calculate heat output of your radiatiors and compare that to the actual heat requirement of the room.

I've attached 2 charts of various types of radiation that will help you can do that. Hopefully your radiators are listed there and you can determine their EDR outputs. You can also take that total, add approx 33% to it, and compare that to your boiler. The boiler should be slightly large than the total number you come up with. Maybe it was too large to start with, and your rennovation reduced your heatloss substantially enough to cause the excessive cycling. Is it an oil steam boiler? Was the burner recently replaced? As you can see, there are alot of factors that can infuence this situation - the venting is a good place to start, but I suspect your rennovation contributed also.

Good Luck

Plumb Bob

>Also, the solution seems wasteful; I don't want to run the heat longer

Your original problem was that the boiler was not heating the whole house. You have to run it as long as is needed to heat the rooms to your satisfaction. Balancing is not going to reduce the flow to the too-cold rooms, only to the too-warm rooms. So it will do what you want done (heat the lower floor) as fast as possible. Certainly you have less energy consumption if part of the house is too cold; if your priority is to use less energy, you can leave it the way it is.

Cleaning the boiler is good (if needed), but it won't help you balance the heat.

Boilerpro_5

You've found part of your problem...

The radiators were sized to heat the house without any insulation. If you insulate the walls on both floors you will tend to reduce the heat load evenly on both floors so the heat will still be balanced after your upgrades. However, when you insulate the ceiling of the upper floor you reduce the heat loss dramatically (maybe half) on the upper floor and much less on the first floor (reduced air leakage). If the thermostat is on the upper floor, which still has big radiators and a very greatly reduced heat loss, the lower floor will be cold.
I believe both plumbers are probably correct,too, as is the recommendation that the main vents are probably too small.
When the boiler is short cycling is it cycling off on the pressure control or the thermostat? If on the pressure control, dirty boiler water (sludge etc), too small main vents, or oversized boiler are all possible problem areas. If its on the thermostat, the anticipation or cycling rate of the thermostat is off. And yes, short cycling is really bad for your fuel bill and equipment life. It also plays havok with system balance on steam systems.
I'd strongly suggest you get a real steam pro in there (take look at find a professional on this site), spend some money to get the system is top notch shape (main vents if needed, good boiler cleaning, address any banging issues, pipe insulation), then look at balancing the system with new vents. If you really want to see exceptional comfort and efficiency, have thermostat radiators valves installed to give you radiator by radiator temperature control on all the rooms or selected spaces.

Boilerpro

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Josh_16

more from the owner -- response to boilerpro

The effect of the roof insulation may not be as big as you suggest; this is a 4-story house and only the bottom story is a real problem. The entire front and rear walls ahve new insulation and one side wall is shared and thus not exposed to the outside. Also, the plumber who worked on the reno did put in a few new radiators where we were missing old ones or they were too damaged, but left the existing system. Both he and the architect advised as to which radiators would be best where and rejected a few swaps I suggested. In other words, I think he gave some thought as to balacne with respect to the radiator size in each room, although I am not sure how much he was thinking about the effect of new insulation (I am not sure he is aware of how much we did). His advice was over the phone and he did not observe the boiler cycling in connection with my temperature imbalance problem. He's plumber B. by the way.

As for the cycling, plumber A does say it is tied to the pressure, not the thermostat. Yours is the first response that suggests he may have a point. The boiler is not cycling because the room where the thermostat is located reaches the required temperature. It cycles a bunch of times before the room upstairs reaches the termperature set by the thermostat. Plumber A does not say not to balance; he says to flush first, see where we stand and then balance.

This is probably more than you want to know, but your comment is very helpful.