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One pipe steam, New addition, what to do...

My house was built in 1945. I have a steam system, one pipe, gravity

drain back. I have currently 5 radiators covering 900 square feet on a

over-fired peerless wbv-03 boiler. (oil fired). I have it set up with

now with a nozzle and such that it's around 85,000 BTU if I recall

(within mfg specs).

So anyway, I built an addition, roughly 620 square feet which equates to two new bedrooms, and a new mater bath.

My boiler has the capacity to heat the additional space, however due to

the construction I can't really put steam radiators in the new part of

the house. For one, the ceiling joists are much lower than the other

part of the basement, so there is no real way to provide a gravity

drain back to the boiler. And two, I don't have any spare radiators and the cost even in the aftermarket of used radiators is high!

So I have a few options. I've been investigating electric baseboards.

We pay .14 cents per kwh here in New Hampshire, which means 1 million

btu is about $41.52 at an efficiency rating of 99%.

In contrast, my oil furnace is around 83% efficient and costs about

$30.32 per million btu. (Oil is around $3.50 per gallon today).

Now, another option I have is converting to a forced hot water system.

My boiler, when used with forced hot water according to mfg specs, can

achieve a higher efficiency rating of around 87%, which would translate

to roughly $28.92 per million BTU.

Now, I'm not an expert at converting, but I roughly figured out the

following and here is where I need help. If I convert the boiler/system

to forced hot water I need the following I think:

Baseboards $450

Circulator pump $200

Aquastat $100

Zone valves $300

Piping $400

Expansion tank $100

Thermostats $100

Zone Valves $225

Total $1,875

This assumes 8 or 9 baseboards, 3 'zones'. I'm assuming 1 circulator

pump and 3 valves are what is needed. Pex tubing, misc fittings, etc.

The alternate option of electricity is:

Baseboards $450

Wire $125

Breakers $75

Thermostats $540

Misc electrical supplies $40

Total: $1,230

I could also cut that in half and just run electric in the addition, but then I would be heating with *two* systems.

Lastly, the folks on the diyforum that recommended I come here and ask questions,  have told me my boiler can be plumbed to do both steam and forced hot water at the same time. However, I'm weary that a call for heat in a forced hot water zone would also create steam in a steam zone not calling for heat.

Advise from the pros ?


-- Joe


  • j a_2
    j a_2 Member Posts: 1,801

    First off don't fear a wet loop, off a steam boiler,installed correctly it will work fine and last a long time,,,rads should NOT heat up...The proper installation with the use of an aqua-stat will be fine....You should however be concerned about your over sized, over-fired boiler that in itself is costing you big bucks and as well as wear and tear on the boiler....I highly suggest cast iron baseboard,you can find it fairly cheap and its easy to install...paint it up with the color of your choice ref. Dans articles about painting rads most important is the last coat...it has an effect on btu output...Any good heating guy can assist you, remember sq ft of space has nothing to do with steam heat and everything to do with forced hot water .....Get up a list of questions to ask your installer if he answers them ALL correctly, on site then you got your guy...If he scratches his head and says he will get back to you with an answer send him along the way...On Elect heat I personally think you downgrade your home to a cottage....resale is not good....just my opinions....Again this site can answer all your questions with just a few clicks, and its free... not a bad deal  j a
  • Rod
    Rod Posts: 2,067
    HW Zoner Off Steam Boiler

    Hi Joe- Since you have extra heating capacity in your present boiler,  I think probably your best option at this time is to run a hot water loop off your steam boiler.  In some circumstances this can done directly off the steam boiler though it might be better to utilize a heat exchanger heated by the boiler water and have a separate circulating loop for the hot water circuit.

    You may also still have the option of running steam heating into the new addition though you will need to check with a steam pro on this. If you look around for them,  good used steam radiators can be found and can be had sometimes for free or for just the cost of scrap metal.

        BTW one of the rules on this board is that pricing is not discussed so I can’t comment on that other than to say that the cost of operation far out weighs the cost of materials/installation so it is important to make your system run as economically as possible. To do this you really need to do your homework or have a pro do the installation for you as there are a lot of design considerations and calculations that need to be done to achieve a comfortable economical running system.

        There are a lot of good books on both steam and hot water heating available on this website in the “Store” section at the top of this page so you might want to check there.  You might also check the “Find a Contractor” section at the top of the page. I don’t think there are any listed for New Hampshire however they do list a lot of very good guys in Massachusetts so you might find one fairly close to you.

         I would stay away from electrical heating as the government seems to be on a program to bring down electricity usage ( example- new light bulbs) so they may soon make the cost of operating electrical heating  prohibitive to force you to change to another mode.

         I’ve attached an article on simple hot water loop off a steam boiler so you can get an idea of how this is done and while this can be done successfully, I would encourage you to go with a heat exchanger as this is far less troublesome in the long run.

    - Rod

  • Steamhead
    Steamhead Member Posts: 16,726
    How much lower are these joists?

    As long as you can keep a 28" "A" dimension, you can run a steam main at a lower level. You can even make the new main counterflow if it'll make the return setup easier. We've done it..............
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
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