Insulation = reduced efficiency?

Garret_4

$6000, oh my. Now I feel better about what my gas bills were last year...

If you haven't yet, get yourself a setback thermostat and set it for "monastery." In our house, in the winter, the boiler shuts off at around 9pm and doesn't come on until morning. Gets a bit nippy at 3 am in the middle of January, but that's what down and wool blankets are for. Keeps the little ones in bed too, they know they'll freeze if they cause a fuss.

I think a smart recovery thermostat is a little like outdoor reset... you can set a deep setback (or off in my case), and a time of day you want it back to habitable the next morning. Then the stat keeps track day-to-day of how early it needs to fire up the boiler to get the house warm in time. As the weather gets colder, it'll start firing up the boiler earlier and earlier... but in the shoulder seasons, the boiler can stay off almost the whole night.

Patrick North

As you've all kindly suggested, our first step in increasing the heating efficiency in our new (to us) home is to insulate the beejeezus out of it. We're dealing with one pipe steam. A big ol' Victorian, the third floor and attic have ZERO insulation, and I suspect the rest of the house has little more. Needless to say, we're looking forward to making out pretty well with fuel savings this winter once we insulate, and when it comes time to replace our aged boiler we hope to be able to downsize a bit. Here's the question- the insulation contractor said that such a dramatic increase in insulation would likely make the boilers (there are two) work less efficiently because of the shorter cycle times, yada, yada, yada. This made some sense, though I can't imagine it would begin to offset the increase in overall system efficiency thanks to the insulation. Still, these are older boilers (1965??) and I'm wondering if this could accelerate their demise.
With all we've had to deal with in this new place (cat pee, bats, various bad mojo) I'm beginning to assume the worst, though this guy also told me I should convert to HW...
Anything to worry about or be aware of, or has the heat finally gotten to me?
Thanks,
Patrick North

Brad White_9

Yada nada

You are doing the right thing, Patrick, intelligently insulating your home. The contractor is correct to a point but I would hope you do not take this as, "Run the system efficiently to heat an un-insulated house".

The boiler will cycle more because, naturally, it has to run less to heat the house. Your radiators are probably adequately to over-sized now. Being a Victorian it may not have the over-sizing prevalent during the post-influenza era, (full heat with the windows open), but let's assume some decent over-sizing such as by the Mills Method, maybe 50% more than you would need.

Now you will likely cut your heat loss by a third, maybe 40 percent by my experience. Storm windows and other things we may assume have already been done? Let's call it 30% savings then. If more due to forestalled infiltration all the better but stick with 30%. Now your radiators are twice the size needed, not 50% larger. Your cycle time will be proportionately more frequent. C'est la Vie.

Going forward, I would (naturally!) do a detailed heat loss calculation, then measure your radiator EDR and compare the two. Next, I would remove and re-arrange radiators to be as close to the room's heat loss as possible. Add TRV vent valves, keep it steam and keep going.

As you know from hanging around here, steam boilers are sized to the radiation, not the heat loss of the house. It is the radiators that must be sized to the heat loss. Here is your opportunity!

chuck_6

Insulation, also check your vents

Patrick:

Listen to Brad. What you also want to do is to make sure each radiator is properly, and that the mains are properly vented. I've had much success with Gorton vents. For the mains measure the length and diameter. Call Ken Kunz at Gorton (908) 276-1323. He can help in terms of which Gorton vent should go on each radiator and the mains, and where you can purchase locally.

Chuck

Steamhead (in transit)

Pat, also insulate

the steam pipes if you haven't already. STEAM pipes, not hot-water.

"Steamhead'

P.S. My offer stands.....

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Keith_8

40+

In my experience 40+ year old residential boilers don't have much life left to begin with. The flip side to the insulating contractors comments about shorter run times being less efficient would be that the longer these babies are off the less oil goes up the chimney. I would be suprised if they are higher than the low 70% efficiency rating.

I agree with the 2 previous posters. Tightening up the house as being your biggest bang for the buck and make sure the system is vented as well as possible. I would add, make sure the boilers are tuned, the heat exchangers and the water side are as clean as possible.

Good luck,

Keith

Larry Weingarten

I'll add...

... that having a blower door test done before insulating will allow you to find and fix the bigger air leaks in the house. This can have as significant an effect as insulation does. So, find someone with a blower door who knows air sealing techniques. It'll be money well spent.

Yours, Larry

joel_19

testing

You should have a blower door test and maybe an infared camera test done . www.comfort-institute.org to find a contractor like yours truly. who does this work. Simply blowing in cellulose may have little effect if the house is not air sealed first . if ballon framed you can have a big impact simply by air sealing the top and bottom plates and all Attic penetrations. This should be done before insulation. Or if using icyneene you'll get both in 1 step.

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Mike T., Swampeast MO

I may be wrong here, but in my understanding of steam the main effect you should see is less frequent cycles as the house will now hold heat much better.

Any steam cycle should find the boiler firing for a rather considerable length of time with the entire system filling with steam. If it doesn't then suspect problems with venting and/or thermostat anticipation. You should however essentially expect more space temperature fluctuation in moderate weather.

Don't forget that steam is a very different animal than hot water. When it comes time to replace your boilers they will be sized by the amount of radiation, not the heat loss. Fortunately however, new steam boilers contain significantly less water than old. This allows them to begin to steam much more quickly thus reducing cycle losses.

Brad White_105

Excellent point, Larry

We both know that infiltration is often the single largest category of heat loss especially in a house that is well insulated. Blower door tests and sealing indeed pay huge dividends. I wish that they were more mainstream and commonly done.

Patrick North

Yep, Steamhead- additional pipe insulation is on the list as part of the overall bejeezus-level insulating project. And it's looking more and more like I'm going to have to save my pennies for a system overhaul from the master. Hopefully I can can replace the rusty main vents with some Wallie assistance to buy some time. In other words, I hope to take you up on your offer at some point, but for a larger scale project. Would you believe the previous owners noted over $6000 spent on natural gas last year?! Hopefully we can tighten things up well enough that a new boiler/piping?/radiator juggling can be designed with a smaller load in mind.

Steamhead (in transit)

Six Grand?

I think we need to get together sooner than later!

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Patrick North

Trying to break it to the wife gently that this is going to be yet another cash-shaped sink hole in the new abode... Gotta love old houses.

Steamhead (in transit)

Tell her

you won't have any money for other stuff until the steam is straightened out. Which sounds like it might be true ;-)

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Patrick North

True, true. Just sent you an email.
Thanks,
Patrick