radiator retrofit

redryder2006

Please excuse the crude drawing I have attached. I will be removing the old failing two pipe steam system from my house this spring. I would like to do as much of the plumbing to prepare for the new boiler (hot water) as possible. Most of the plumbing will be in a tight cramped crawl space so I would like to use a supply and return manifold with a dedicated supply and return line going to each radiator to keep everything easily accessible in the walk in portion of the basement. I will be reusing the cast iron radiators with TCV on each unit. There will be about 12 radiators in the new system. The boiler will be a wood burning unit with a fuel oil back up, a on demand propane DHW heater will be used in the summer for hot water needs.

Questions:
Should the DHW be plumbed in parallel or in series?
1/2" pex for each supply and return line?
Someone explain to me please where the circulator pump(s) should be?

Steamhead

Why are you replacing the steam? What is "failing"?

redryder2006

The steam piping has deteriorated to the point that there are numerous pin hole leaks popping up in the crawl space and inside the walls. If I'm going to replace all the plumbing i'd like to update the system to hot water.

Steamhead

Something tells me you might have a water quality problem. Steam piping usually looks pretty good when you take it apart (wet return lines are another issue). In all the years I've worked on steam systems, I've only run into one installation where the steam pipes leaked like that. The water was OK on that one, we think it must have been some poor quality pipe. Only certain parts leaked.

First thing I'd do is get your water tested. A leak in a steam pipe is one thing, but in a hot-water pipe or radiator it can cause some major damage.

Ironman

You cannot take domestic water directly from the boiler like it's shown in your drawing.

It looks like you may need a little help with designing. There's a WHOLE lot more to HYDRONICs than simply running pipes.

redryder2006

I know its cant be taken directly from the boiler. the boiler includes a dhw coil. I'm just not very good at drawing in detail.

Rich_49

What boiler would you be thinking of using for this ?

Ironman

redryder2006 said:

I know its cant be taken directly from the boiler. the boiler includes a dhw coil. I'm just not very good at drawing in detail.

Your best option would be to install an indirect water heater and not use the tankless coil or instantaneous water heater. You'd get much more hot water, with no issues, and save considerably on fuel.

KC_Jones

Are you adding radiators or just using the ones you had from steam? You mention reusing radiators. Have you verified the ones you have will work on hot water (not all of them can be converted). You lose output when you change them to hot water. Have you done a room by room heat loss calculation and verified you will have enough capacity? I am a homeowner and pretty hard core about DIY, but honestly these systems are fairly complicated. My suggestion to you would be to spend the money on a design consultant and have them lay out your system for you before you start running pipe. There are so many people that come here after a professional installed their system and it doesn't work and then end up spending even more money to get it fixed. In the end you will spend the money either once to do it right or twice once to do it wrong and a second time to get it right. I am not trying to discourage you nor be rude just honest. You can get a ton of good information from this site from a lot of very helpful people, but in the end you still need a good design and plan. There are plenty of contractors on this site that do design and consulting, if it was me I would start there. Of course it's your house and your money so in the end it's your decision.