New HE Boiler for old house with radiators

Weasel

Replacing a 30 year old oil boiler with gas.  Was told by one contractor to stay away from high (96%) efficiency boilers for this very old hot water radiator system because they don't work well for this type application and require a lot of fine tuning at installation and numerous call backs to debug.



Alternative is a lower efficiency  non-condensing unit.



Plan to be in the house a long time, so would appreciate the higher efficiency for fuel savings over the long haul.



Second contractor offers a Munchkin high eff condensing unit and says no problem.



Wisdom appreciated!

kcopp

First guy.....

has no clue. He needs to be educated . The High Eff units are perfect for those set ups IF piped properly & sety up w/ a combustion tool.  I am not a munchkin fan... too many issues and the HX is very narrow. Be sure to have the system cleaned out and flushed of old debris.

Ironman

The First "Contractor"...

Doesn't know what he's talking about. An old system like yours is one the best candidates for a mod/con and it's not difficult to do. We do them frequently with great results and very satisfied customers.



I don't have time at the moment to go into details, but here is a recent thread about this. It's a recurring topic around here:



http://www.heatinghelp.com/forum-thread/136255/NG-conversion-diameter-of-old-raditor-pipes#p1230420

Weasel

Narrow HX?

Thanks for the reply.  What is the issue with a narrow HX?  Another contractor quoted a Utica unit and a third a Weil McLean. Which is best per your experience? 

Weasel

Munchkin?

Any experience with Munchkin boilers?

kcopp

The narrow HX....

may plug up w/ the old radiators being in  the system. There is a lot of old junk in there. If a chuck of old iron get on the HX it may create a hot spot and you may have a leak... That hx warranty is now void. Munchkin , Trinity, Peerless all use that same Giannoni HX. I don't have a lot of confidence in the Aluminum block boilers either...

AFred

If your asking...

I still think you cant go wrong with an 84% cast iron natural draft boiler. So few parts and it can be neglected for years and it will keep on truckin'. I think the cast iron will outlast.

If you want to go condensing, I recommend Triangle tube, best HX on the market.

-Andy

James Day_2

Boiler

Go with the Mod/con you won't regret it.  Cast iron gas boilers are a dying breed.  As far as best heat exchanger on the market, I think Viessmann holds the title on that one( jmop)      James

Weasel

Maintenance

Just one last question.  Will savings 96% vs 84% in fuel will be eaten up by service needs of a complicated system?



Thank you all for your comments!

CMadatMe

Performance

Like any high performance piece of equipment service is a necessity to get the full and on-going savings from any high efficiency piece of equipment. My boiler choice would be Viessmann Vitodens #1 and Triangle #2.

Would have to do a heat loss, measure emitters to provide the best solution for the job. If any of the contractors quoting you haven't done this, they cannot provide you the best options. Condesing boilers and cast iron go together like a hot dog with the bun.

zacmobile

complicated

What are you referring to as complicated? The installation piping requirements or the boiler itself? If you just have one temperature requirement (ie. oly rads) then installation would be as simple as they get, pretty much in & out of the boiler, or possibly with a low-loss header or other such thing to keep the boiler happy & that's it. As far as the boiler being complicated, I suppose they are on a certain level, but I have found Viessmann & Triangle Tube boilers to be extremely reliable, never had a call back with either of these.

kev

Do we know

if the radiators are over sized? If the rads where sized properly when installed a condensing boiler may never see those low operating temps that give you high efficiency.  Just because they are cast iron rads does not mean they are over sized. A non condensing boiler with outdoor reset may be smart choice. 

CMadatMe

I tend to Disagree with You

Only need design temp at design day. How many design days do we see in a heating season. Three to Five? I still could get into condensing mode in late Oct, Nov, most of Dec and then March, April. Even if we are not in a condensing mode but using limited rate of modulation a condensing boiler would still be 89-92%.



I haven't found a house yet with rads that wasn't oversized. Homes with rads tend to be older homes. Most have seen upgrades in windows, siding, and insulation.

Paul Pollets

Replacement

I agree that a mod-con would work well with your changeout. Three suggestions when replacing system: Find a competent contractor  with ample experience.. I'd make sure all existing radiator valves were replaced with Thermostatic Radiator Valves (TRV's) for optimum performance and balancing.  Make sure the new bladder type expansion tank is properly sized for the load.  The mod-con generally runs at 90-92% efficiency when running a radiator zone.  The combustion analysis will tell.

gn

stuck with cast iron

I replaced a 70-year-old gravity cast iron coal-burning (converted to NatGas) boiler with a Burnham Series 2 a few years ago after talking/researching the topic pretty extensively. The PVC piping the mod/con guy was going to have to route all over the place to get out of the boiler room, the condensate that needed piping and a pump to get over to the floor drain, the more-complex control system (read lots of things can go wrong), the $3000 higher all-up initial cost, and the $200-$300 yearly inspection/tuning/cleaning he told me to expect to stay efficient made it easy to stay with the dumb CI boiler and pay perhaps $150 more in fuel costs each year.



I am very happy with my choice.

James Day_2

high efficiency

Any boiler, whether it is high efficiency or standard should be serviced anually.  As far as venting, you can run you exhaust through your existing chimney using a special plastic (PP) Liner. 

CMadatMe

I'm Glad Your Happy

With your choice. Everyone has their own happiness. Still left alot of money on the table when looking at long term pay back. A condensing boiler does not necessarily need a yearly maintenace. A smart professional that understands hydronics, sizes and installs proper systems would have sold you a service contract. Now that yearly maintenace fee is out of the equation. He gave you somthing more valuable then any yearly maintenace fee. His professional knowledge and expertise to give you a piece of mind that you will be warm and cozy through the heating season without a worry if by chance something went wrong. He gave you the comfort of knowing he trusts the equipment he is installing.



Look at your fuel bills since day of installation. Not dollars, therms used. Compare the heating degree days, is that lack of maintenace on a cast boiler costing you money? Whether it's ten bucks or a hundred bucks that's 2 gallons of gas or a phone bill. Either way it cost you money.



Nothing in this world is maintenace free if you want that product to perform to its potential. Quick question..Why didn't he just use the existing chimmney as a chase?

Steamhead

When considering a mod-con

make sure there is a safe place to exhaust it. This type of boiler cannot use a standard chimney, so a safe alternative place is needed. This must be a foot above the highest recorded snow accumulation for your area, and with proper separation from doors, windows and other penetrations.