Cast or Condensing: Which for a Retrofit?

Heatmeister_2

This is the kind of information I am in need of. I am in Minneapolis and am having a tough time finding a pro with the knowledge of those that frequent this sight. Only 1 contractor I spoke with did a heat calc or even suggested it.

"Find a pro" lists nobody in my area. I won't do this myself since I know my limitations. I am very tempted to approach someone out east or other area who is a "real pro" and ask them to fly in for 2-3days for the first stage/initial install. Anyone one ever done that over a weekend?

Heatmeister_2

Cast or Condensing: Which for a Retrofit?

My apologies upfront for asking this difficult to answer question. I know many factors are involved, but after several months of researching and attending the MSP wetstock event, time is running out and I am getting conflicting answers about what approach to use. So here it goes along with a picture.

I have a dead WM HE series 167k/137k input/output. It is a monoflow system which has ONE 1 1/4 inch supply line and 3 returns with 3 B&G pumps on the return end (1)1/6 and (2) 1/12 hp. 3 zones and I run Copper Fin BB. I would like to also add at some point some staple up radiant between floor joists and maybe infloor for an addition down the road. However, the majority of my heating elements are and will be BB, irrespective of any infloor heating elements.

IF I install a condensing boiler, will I see immediate fuel savings with BB application as the primary heating source? Never mind cost justification. I know a condensing unit will require more work up and cost more upfront. I am ok with that. But, if my BB runs at say 180degrees whether 32 or minus 32 outside will I benefit from a condensing application along with a outdoor reset which most have or come with. I cannot find anyone in my area (installers) that can answer this question yes or no. I know radiant is ideal for the application of condensing, but unfortunately I will not be tearing out my BB and putting in Panel rads etc... Just too labor intensive and cannot find ANYONE(lord I've tried) knowledgeable in this area wiht FIRST Hand experience.

Also whether, If I go condensing or Cast Iron, should I cut out the (3)B&G pumps and put jsut 1 high flow rate pump on the supply side and use zone valves to control flow rates etc?

Again, sorry for the difficult question being posted. I know when approaching a solution there are several ways to go about it.

Here is my dead soldier

Constantin

Some thoughts...

Well, look at your heating season overall and ask yourself the question: On how many days do I need 180°F hot water? The answer is, if your BB is sized correctly, on 5% or fewer. Furthermore, if your BB was put in before the advent of insulation and other weatherization improvements, it may work at much lower temperatures than you think.

Go away from the notion of bang-bang controls and embrace outdoor reset-controlled water temperatures. Only a low-mass, condensing, and modulating boiler can take advantage of those. Such boilers are the key to the lowest-possible energy consumption.

Your radiant staple up zones are likely to require a different temperature than the BB upstairs, yet a number of solutions exist to meet that market, such as two-stage thermostats where the radiant zone tries to keep the room warm and if it doesn't make it, supplement with the baseboard.

As for experts in your area, where are you located, and have you tried the find-a-pro service yet? Such a person would be able to pipe the system as needed... and if you want to do the work yourself, you could consider giving Rob at Northeast Radiant a call. They offer lots of consulting services, including system design and assembly.

J.C.A._3

First.....

Do or have a complete heatloss performed. You may find that a condensing boiler may well work with the existing baseboard. Maybe not all the time, but with some type of outdoor or indoor reset, some,if not most of the time.

The best thing that you can do to enhance any type of fuel savings will be to tighten the envelope, (blower door test and seal where it shows the big infiltration)Heck, if you have the space, add some more baseboard to make a condensing boiler work all the time with it.

For electricity savings zone valves and an appropriately sized pump WILL save alot of money, but please don't forget some type of pressure differential bypass to make sure they work properly ! Lastly, insulate the boiler piping. The btu's lost on the way to heating elements are usually over figured into a heatloss, but can lower the "piping pickup factor" quite a bit, especially in an unheated basement.

Want to save more? How much money are you willing to spend? You could also look to TRV's ....With a mono-flow system, the only sticking point is the space needed to make them fit properly.(baseboard enclosures are a PITA to work in :^( ) Maybe remote mounts????

You're right, there are lots of other things to consider. Hope I gave you a few more to add to the fold. Think positive...anything you spend on making a heating system more effecient will come back to you in spades on re-sale. Chris

Tony_23

180F

First, forget the notion that your bbd is going to run at 180 ALL the time. It hasn't, it doesn't, and it won't. It may have been designed to at design temp difference, but that doesn't mean it does always. Warmer days the system short-cycles and the water temp won't get there, I promise.

Get a MODULATING, condensing boiler with outdoor reset and start saving fuel costs immediately. Anyone who says you won't doesn't have the experience to know.

Steve Rockwell_3

Condenser Is The Only Way To Fly

I live in Grand Rapids, Michigan, so I am a bit south of you, but had the same concerns. My house is about 90% baseboard, the remainder ci rads. I decided to go with a Weil-McLain Ultra 155.

The system typically runs at 130* and below, and our 1920's era home that was incredibly cold before is now very comfortable.

After tracking out natural gas usage since we installed it in late November 2004, usage during the heating season was about 38% lower than with our old boiler. Summer gas usage with an indirect is just less than half that of a separate direct unit.

The math didn't work for any kind of decent payback when I purchased the unit, but with consequent price increases, and perhaps more to come, that is changing.

Mark Hunt

Ditto


On an average, my customers report a 35% reduction in therm usage.


Hope this helps.

Mark H

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Heatmeister_2

WOW! Did you ad any additional Copper Fin BB or CI rads or did the increased comfort just happen b/c of the unit, i.e. outdoor reset and technology improvements? How many zones do you have? Are you running one outlet pump with zone valves or multiple pumps? What brand and size Indirect Hot water heater did you end match it up with. Thanks

Steve Rockwell_3

The only modification we made to that side of the system was to add TRV's on the cast iron rads. This succeeded in keeping the oversized rad in our master bath from overheating my wife, which was perhaps more important than the savings!

The Ultra does include outdoor reset, and it is fun to watch the system temps respond to changes in temperature. We have two zones, and the system is running on constant circ. Outdoor reset and CC are to thank for the increased comfort in the home. The bb just puts out enough heat to keep things at the desired temp. There were a few spells where the system ran nonstop at 126* for days on end.

We put in an Ulta 40 indirect, which I think is only 36 gallons. It replaced a 50 gallon direct, and has we have yet to run out of water, even with guests in the house. You may or may not need something larger if you have a large family.

clammy

modulating condensing

i presently have 4 jobs out there with condensing modulating boilers .The HO have reported from 30 to 50 % reduction in there gas bills durning the heating season and these are with baseboard one a complete new install using slantfin 80 and sized for a max temp of 160 .The HO did take my advice and tighten the house up with insulation windows and doors and found that the new system properly sized had cut there gas bill in half and that was after adding about 1600 sq.ft to ther house and doing radiant for there garage there system rarely short cycles and only in the dead of winter at design does it hit 160 .I have found that i like using pumps over zone valves if the money is there, but either way these boilers do reduce your bills but tightening your building enevolpe is just as important the boiler only truely shines when all the homework is done .I can state that condensing modulating boiler do work and reduce fuel bills on baseboard system as long as the boiler in question is installed properly and all the homework has been done leaving any quess work not to be .peace clammy