I need some help and it seems these forums are well visited and get great advice. So I am trying it for the first time.

My oil boiler was killing us in heating cost. So this summer I track down a guy in upstate NY that sells refurbished coal boilers. Now I am trying to install it and all those great friends who are plumbers now have busy schedules so I am left to my self for the time being. So here is what I am trying to set up.....

Boiler feeds new radiant heat install and has coil for domestic hot water.

So here are the questions I have...

1)Where does my coil piping connect to the water supply? Before or after my air eliminator?
2) Can o2 barrier pex be used anywhere before the manifold that feeds the radiant heat tubing? I know on hot water heaters a min of 18" for heater before pex so is there a rule of thumb?
3) Getting mixed messages from plumbers... circ pumps on supply or return?

I know I will have more questions but for know Thanks to all those who will reply

 

I think we need to ask you a few questions before we can answer yours...

Have you somehow determined that heating with coal is going to cost less than heating with oil? Have you set up a coal bin and located a delivery service? I presume you are prepared to shovel the coal...

Does the refurb boiler have an automatic feeder?

Is this 'new' install in ADDITION TO, or IN PLACE OF a previously existing system?

Is it properly sized to meet the heat load (determined by a proper heat loss calculation) in order that the home can be properly heated?

Are you aware that you can not run full temperature water to the radiant system, that it must be 'tempered' such that the water running in the system is around 100° (or thereabouts)?

How did you previously heat your domestic hot water?

We'll get back to your original questions, but off hand there seem to be some misconceptions in them that we should be able to help you with.

 

Yes I have determined it is cheaper. Coal is about $12.00 per million btu and #2 heating oil is around $30 depending on fuel prices. Coal bin is built in basement.

Yes has an automatic feeder.

Yes it is properly sized to meet the heat load.

Yes I have a mixing valve for before the hot water goes to the radiant manifold.
Radiant heat system is new. Had cast iron radiators before but wife wanted warm tiles in kitchen and bath.

Have an electric water heater. Was told the coil from the boiler can feed into water heater and only when level in water heater drops will it use electricity.

 

OK then... let's go with your questions now

You mean the domestic coil in the boiler, correct? If so, that domestic coil is completely and totally separate from the boiler plumbing. It has nothing at all to do with the air eliminator.

AFAIK, there is nothing that says you can't use the tubing everywhere. I don't understand why water heater manufacturers recommend that 18" spacing... unless it has something to do with temp/pressure ratings on NON O2 barrier tubing.

Because of 'old school' vs. 'new school'. "Plumbers" should not really be relied upon for advice on a heating system. Yes, they are all pipes, but there are unique considerations that need to be made for heating systems.

Modern theory says that the pump goes on the SUPPLY side, with the expansion tank and air eliminator on the suction side of the pump. Google the term "Pumping away" to read more... and ignore any porn sites that might come up in the search.

 

By this you mean the radiant system, right? and I'm guessing that the boiler was also sized properly?

 

Both are size appropriate. The 1st floor is approx 1000 sq feet. 7 zones or runs of radiant o2 barrier pex each less than 300'. Bought a 9 port manifold for any expansion projects. Boiler is above what I need for my house. EFM 350. 188,000 btuh. Want to be ready to do the second floor (1 1/2 floor, 3' wall then roof). It has never been heated since before we bought the house 2 years ago

 

I've heard that some heater manufacturers specify that water no hotter than xxx° should be fed to the inlet of the heater. I'm not sure why... or if it's even true...

What they were trying to tell you is that you can 'preheat' the water before it enters the electric by running it through the coil first. So, the cold supply would be fed to the inlet of the coil, then the outlet of the coil to the inlet of the electric. Be aware that the water coming from that coil can be VERY EXTREMELY HOT! If the boiler is at say 180° high limit, then the water in that coil coming out can also be... and maybe this is what the electric tanks don't want to see? Like I said, I don't know the reasons for that.

Water that hot will obviously cause severe burns immediately...

There are a few other more complicated strategies to using the boiler to preheat the water in the electric.

One would involve setting up a small pump with a thermostat on the heater that would circulate water from the heater through the coil of the boiler.

Lastly, the LEVEL in the water heater will never drop. It will always be FULL of water. I think you meant to say the TEMPERATURE in the water heater?

 

Thank you for the lesson. I didnt know what I meant. That was what I was told. But the temp of the water makes more sense. Thanks

 

Our family and all our neighbors burned coal in the '50s for home heating. Nobody there does now. Reasons: dirt, coal dust, smoke, arranging coal deliveries, cost for delivered coal, clinkers, and difficulty in matching heat supply to need (too hot or too cold). Back then, there were several local coal suppliers for us - how many do you have?

When you quote the energy cost of coal, $/MMbtu, what is the energy content of the fuel? 12,000 Btu/lb would be maximum for a premium coal.

Coal is used for industrial and utility fuel. They have the experience and skill to handle it. Few of us in residential heating do. I wouldn't change from oil (or gas) to coal for residential heating.

 

djthorniley, an EFM 350 is a great boiler. I heat my house with an EFM 520, and it cut my heating costs in half. Where do you live in Upstate NY?

Nothing against the guys on this site, but if you have coal-specific questions related to the EFM you should join us on the nepacrossroads.com forum...there is an entire subforum dedicated to EFM coal boilers.

Back to your piping questions - Plenty of people have hooked a tankless coil in series with the electric hot water heater...I have also hooked up a tankless and a small indirect in this manner.

NJ Trooper - I think somewhere there may have been a tankless coil in a steam boiler hooked up to a tank-type water heater with a plastic dip tube...I can see where that would cause problems. In this case, a hot water boiler shouldn't see such scary temperatures. Yes the first couple gallons from the tankless will be very hot, but it will be sufficiently tempered by the larger volume of water in the electric tank. A mixing valve mounted on the output from the electric hot water heater would ease any concern of scalding.

As for the radiant system, I would consider piping the EFM in a primary/secondary fashion. By doing it this way you can avoid excessively low return temperatures from the radiant system stressing the boiler, and you won't need to pipe a separate bypass like EFM recommends in their manual. Control the primary circulator with the triple aquastat to allow DHW production from the coil. If you want a sketch or something just ask.

 

Oh man would I love a sketch. Something about visual learning.
I joined nepa but wasn't going to post until I gave sufficent time to let the man I bought the boiler from a chance to respond to my emails as he is a frequent commenter on nepa. So didnt want him to think my asking for help was just to shame him or something like that. But it has come to the point I cant wait any longer. Good guy but we cant ever seem to get on the same page even with email. I live in Chatham, 25 mi southeast of albany near mass border

 

Don't worry about asking too many questions. No one is born with the knowledge to install a boiler, you have to learn.

Check your private messages. I have some other questions that don't pertain to the install.