Currently, gas radiator steam heat - considering switching to hot water heat

bradykp

Hi,

My house was built in the 1920s, and I recently had a home energy audit performed, and will be having some insulation work done, as well as replacing my steam radiator furnace that is approximately 21 years old, to upgrade to a more efficient furnace (the state is running a program right now with 0% 10 year loans for up to $10,000 on home energy improvements). I was going to go with simply a new furnace and a tankless hot water system, but the contractor I'm working with seems to be a big fan of converting to hot water radiator heat, because the furnaces available go up to 95% AFEU, rather than 83%. Also, they said this could be me hot water heater as well.

One additional thing to consider is that we're adding radiant floor heating to a kitchen remodel project off of whatever system we choose.



I'm wondering if converting to hot water over steam is really worth the effort? Any advice is highly appreciated!

Steamhead

Keep the steam

first of all, there is no way the state's 0% loan amount will cover something like that.



If he's planning to use the existing piping and radiators for hot-water, they may leak. A hot-water system runs at ten times the operating pressure of a steam system. I've seen places where this has happened and we decline to work on them. Too much liability.



And your radiators may not be of a type that will work on hot-water, and they may not be big enough to heat the house on hot-water. Or if they are, they may require water so hot to do the job, that a 90%+ condensing boiler (NOT furnace) would not run at its best efficiency. These things must be kept below 140 degrees or they won't condense.



The most cost-effective way to decrease your fuel consumption is to put your steam system into peak condition. This is not hard to do, and if the contractor you're talking to doesn't know how, find one who does.

Charlie from wmass

If your contractor is calling it a furnace

You need to find another contractor. Steam can be as high as 85% efficient and will not require all the pumps and wiring hot water systems need. The 95% efficent boiler will only be 83% efficient if the water temps are not kept quite low. This means lots of radiation to utilize low temps.

bradykp

conversion

Sorry -I I meant boiler. I haven't gotten used to using that term.



They have said they've done it in a number of houses in my area and they did say that it doesn't always make sense. They mentioned it depends on the radiators I have. But I didn't realize they could be too small for the space. I've gotten a lot of great referalls for this contractor so I am pretty comfortable with their work and experience, but I will definitely bring these points up. I left out that I also get a $5,000 credit from the state. So $10,000 loan plus $5,000 cash. I am waiting on the full estimate if I convert.

Charlie from wmass

Price is one thing we do not discuss as

it is a big world and different areas have different costs related to working there. WHat region of the world are you in?

bradykp

understandable

I am in NJ, and I understand it varies across the country. Mostly I am just looking to see if there is much benefit to switching to the closed system vs the steam. I guess the boiler options are limited to an 83% unit with boiler (not sure why not the 85% if you say that exists - does it have to do with the btu sizing?).



Thats the primary reason I posted...so I already have some good info to ask the contractor and plumber when they come out. Any more things I should consider/bring up?



Thanks for the help!

Steamhead

85% steam boilers

are pretty common, and the Burnham MegaSteam boiler is 86%. Are you burning oil or gas? 

bradykp

gas

I think the brand starts with a w. I will look it up though. Supposedly there weren't many boilers small enough in the 83%category rating. I will ask about 85% though. That's another thing...the current boiler is around 150,000 btu I think and the new one is going to be 250,000...that sounded odd to me. But they said that the boilers wont run at the full btu if it isn't needed? I am sure I am not wording that correctly...hope it all makes sense

Jean-David Beyer

I am in New Jersey too.

I am in New Jersey and I converted from oil to gas in early 2009 (after the end of the heating season). It was, and still is, a forced hot water system, but is now a mod-con with outdoor reset, where the 60 year old boiler was just a constant temperature boiler with no reset. At that time, I got a small rebate from the state and the $1500 one from the Feds. I also got a small rebate from the state to remove my in-ground oil tank, and a promise of a huge grant for remediating the oil that leaked. This last grant is being held up for about three years because the state is short of money.



With the present governor, I cannot imagine you will get the rebate from the state you mentioned, larger than the one I got with the previous governor. You may want to check this directly with the state to be sure it is correct. Similarly, my understanding is that the feds are only giving 10% of what I got.

Steamhead

Doesn't sound right

how is a larger boiler going to use less fuel? Did they do a heat-loss calculation? 

bradykp

less

I asked about the higher btu, they said it doesn't run full strength or something along those lines. But I do know they need to prove to the state that my energy usage drops a specific percentage but I will ask again

Steamhead

Something tells me

they didn't do the heat-loss calculation.



One of the claimed advantages of a modulating-condensing (mod-con) boiler is its ability to ramp down the firing rate on milder days. But they can only go down so far, beyond which they just turn on and off in the usual manner. So it's especially important to not oversize these things.



There is no way a boiler so much bigger than the one you now have, being used to heat the same space, is going to save energy- even if it can modulate down to some extent. No way, no how. And with the inherent risks in these conversions, and all the unanswered questions, it makes even less sense.



Keep the steam system and optimize it. That will give you the most bang for the buck.

bradykp

nj rebate

This is the program: http://www.njcleanenergy.com/hp

bradykp

thanks for the help

thanks for all of the feedback. I'm meeting the plumber tomorrow night, and i have my list of questions.



1.       Conversion of existing pipes and radiators to hot-water. How can we ensure and what guarantees are there on the plumbing against leaks?

2.       Hot water system is 10x the pressure of a steam system?

3.       Are the radiators big enough to heat the house on hot water?

4.       85% AFEU boilers exist?

5.       Burnham MegaSteam boiler is 86%?

6.       What is the heat-loss calculation?

7.       “modulating-condensing (mod-con) boiler is its ability to ramp down the firing rate on milder days. But they can only go down so far, beyond which they just turn on and off in the usual manner. So it's especially important to not oversize these things.”