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Convert Steam to Hydronic

Merlin Member Posts: 6
We are faced with replacing a residential Weil-McLain oil-fired steam boiler in a 5,000+/- sf house built in 1939.   The individual heating units are fin tube convectors built into the walls. 

Natural gas is not available so we have to decide (1) whether to convert from the present vapor steam system to hydronic heating and (2) whether to stay with oil or switch to propane.   

The present use of the house varies dramatically, from one person at home for most of the week to twelve people visiting for extended stays using all five bathrooms and six bedrooms, obviously a situation that would benefit from a zoned system.  We presently heat our hot water with the boiler and would like to make the right decision regarding that as well (we definitely want to heat the water with propane, but are not sure of the most efficient type of heater). 

We sought advice from several contractors who say they are knowledgable about steam heat.  Our initial goal was to try to maintain the steam system and heat the garage wing with a separate hydronic boiler, provided the new steam system would result in substantial fuel savings, and run a loop off of the boiler to heat a  finished area of the basement.  The garage wing has always been cold and now is used only when we have guests so we thought we would save fuel by achieving a zone in this area.  Also, removal of the steam pipes would allow for better use of the garage space.

We are also remodeling the Master bedroom suite and three of the four convectors will be exposed during demolition.  If we are converting to hydronic we would like to know if we can/ should replace the convectors with radiators, at least in the bath and dressing area where the built-in aesthetic is not important to us. 

We also researched tankless propane water heaters and asked about installing one or more of these to save on fuel and water bills.

Every contractor who has evaluated the system has spent a lot of time, and they all recommend something different.

No one seems to like the tankless water heaters, but I don't get the sense that they have much experience with them.  They point out that the cost of installation may never be realized in fuel savings, which may be true.  Some have described a loop that would solve the problem of wasted water.

As for the heating system, we have received strong warnings not to convert to hot water because of the possibility of leaks and equally strong advice to convert to hydronic so that we can zone the heating system and save on fuel.  Meanwhile, the hot water pipes are leaking in three bathrooms (I guess the copper has a given life and it is ending!) and we are paralyzed regarding the repairs because we cannot make a heat/ hot water system decision.

I have read some of the advice here and I am not sure if we have a one or two pipe system; I am not sure what it means.  I have been told that the system is a low pressure vapor system, that the pipes are iron  The convectors appear to be copper.

Advice would be greatly appreciated!


  • gerry gill
    gerry gill Member Posts: 3,078
    well, here is my 2 cents.

    1- the convectors were sized with the assumption that the temperature inside them was 212 degrees. So they may not be big enough to heat the rooms on the colder days with a cooler liquid in them.

    2- my co-worker converted his steam system (vapor mouat) to hot water and put in a higher efficiency water boiler, and his gas bill went up! We converted back to steam and his bill went back down. Go figure. Course the system (yours too) was designed for steam.
    Serving Cleveland's eastern suburbs from Cleveland Heights down to Cuyahoga Falls.

  • Steamhead
    Steamhead Member Posts: 16,715
    edited October 2012

    you can zone a Vapor system room-by-room with thermostatic radiator valves. No need to undertake an expensive, risky conversion just to zone the system.

    Then there are the possibilities of leaks, etc that have already been covered. Also, some steam convectors have balancing orifices built into them. These will be noisy if you try to run hot-water thru them.

    Don't convert it.

    As to boilers, you can't go wrong with a Burnham MegaSteam.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,576
    Decisions decisions!

    It is difficult to have to consider all these things, and then try to achieve some balance in making a decision.

    One of your preferences I see is to do without the steam pipes in the garage, and that could be done by converting that area to hot water heat fed from a hot water loop from the new steam boiler.

    The rest of the house could remain steam, but with all the little problems taken out of it. The radiators or convectors must be tallied up for their heat capacity (EDR) and the new boiler sized from that figure. The system at one time was perfectly even, and economical, so return it to that state.

    As far as the hot water, the boiler could handle that as well, but with a bigger storage tank, or two for the peak periods.

    Where are you located?--NBC
  • Danny Scully
    Danny Scully Member Posts: 1,415
    Sorry, this always bothers me

    Sorry, this always bothers me...steam is "hydronics". Hydronics refers to heating systems that utilize water as a means of heat transfer. I realize this helps you I no way, and for that I'm sorry. This just always bothers me, and believe it or not this is a common post. In reference to your post, however, there are a lot of things to consider. Many of them have been outlined in this post, but what it really comes down to is the quality of the contractor you hire. With these posts, and your qualified contractors suggestions, you should be able to come to the right decision. Good luck Merlin.
  • Rich_L
    Rich_L Member Posts: 81
    edited October 2012
    We Got Steam Heat

    Check out Dan Holohan's book "We got Steam Heat" available on this website. I just read it and I'm a contractor. I wish all my customers would take the time to read it. Here's a direct link: http://www.heatinghelp.com/products/Steam-Heating-Books/25/61/We-Got-Steam-Heat-A-Homeowners-Guide-to-Peaceful-Coexistence  The little you spend on this book will educate you and allow you to make well thought out, intelligent decisions based on what you have now and what you are considering. It will also give you the info you need to sort out the good from the bad (knucklehead) contractors and make a sound decision based on what they're offering vs what you may really need. It's a pretty quick read with information delivered in "layman's terms". Educate yourself before making this big investment in you and your family's comfort!

    That said, whom ever you choose MUST figure out if the convectors you have now will adequately heat your home with lower temperature water. If so, and only if so, you may save by using a higher efficiency boiler. Bear in mind a conversion to water will bring a need for more pumps and controls and the required electric expense to run them. It's likely minimal but worth considering. You've already mentioned the need for leak testing which could help you decide as well. Here's a link to an old thread about converting with a lot of useful info: http://www.heatinghelp.com/forum-thread/70267/Converting-one-pipe-steam-to-hot-water

    Lastly, if it were me, I'd stick with the steam and upgrade the entire system.  At least as the budget allows. Nothing short of in-floor radiant heat will be as comfortable. Have the contractor size the new steam boiler based on the EDR (equivalent direct radiation) NOT a heat loss on the house, upgrade or check vents, traps, controls, etc as need for optimum safety, performance, reliability, and comfort!

    Best of luck with your decisions!

This discussion has been closed.