Heating options for garage + house

[tommyp]

I am in the process of planning a garage addition to my existing house. The garage is going to be 30x38 two bay on slab with living space in the back. Located in Northern VT.

I am trying to decide how I am going to heat. I am converting the house to Natural gas. The current house is small, 1000sqft. We usually heat it mostly in the winter with a pellet stove. It has oil forced hot air but we only use that on the coldest days if even. It also has an off peak hot water heater.

So I am considering running radiant in the new garage/addition and replacing the forced hot air system with something. I am just struggling with a heat source setup that would make sense financially to run everything.

Is a regular NG boiler the way to go? I am trying to wrap my head on how to mix DHW radiant and probably baseboard. Or if this is the best way to go about this? Maybe keep the radiant totally separate on something like a vertex and just run a wall mount space heater in the house. Then another on demand hot water heater for DHW.

Any thoughts on how you would proceed with those mixed needs would be appreciated.

 

[kd3pc]

First you will need to speak with the authority to make sure you can use one system to heat both units. For sure, you have to have separate systems with forced air -- such that air exchange between garage and house can NOT happen.

Multiple zones off the NG boiler would probably be the most efficient and lease expensive long term, but I like and always preferred hot water heat over forced air.

 

[tommyp]

First you will need to speak with the authority to make sure you can use one system to heat both units. For sure, you have to have separate systems with forced air -- such that air exchange between garage and house can NOT happen.

Multiple zones off the NG boiler would probably be the most efficient and lease expensive long term, but I like and always preferred hot water heat over forced air.

Ah yeah there won't be any forced air in the new setup. I am going to remove the current furnace. There isn't really a way to run ducting to the addition anyway. Well I guess I could but it wouldn't make sense.

I am just concerned about running a radiant loop off of the NG boiler. I wouldn't get a condensing boiler but is the radiant temps too low for a normal boiler? I would probably be retrofitting baseboard in the house, plus the radiant in the addition plus something for DHW.

 

[dfiler2]

You would use a mixing/tempering valve on the radiant zone. It's very common to run both on the same boiler. That's one of the beauties of using water to transfer heat.

 

[jonjon1]

Are you doing central air?

I would maybe put a cast iron ng boiler sized to take care of the addition and the existing.
If your house has duct work already and its in working order, I would add a first co air handler http://www.firstco.com/Products/Multi-Family-Residential-Products/Wall-Closet/EVBQ-(Variable-Speed) as one zone for the existing construction, then add a fphx to run the radiant as another zone, and have a zone for the addition and a zone for the garages floor off of that fphx, both low temp radiant...

Now at this time you can use an indirect water heater but I would not, I would run a heatpump water tank, or a tankless rinnai, etc. I don't like running a boiler sized to heat an entire house just to make hot water, its a huge waste...

 

[tommyp]

You would use a mixing/tempering valve on the radiant zone. It's very common to run both on the same boiler. That's one of the beauties of using water to transfer heat.

Ah ok. So a tempering valve that would add some hot water from the boiler and mix with the return from the floor.

Something like this would probably work for my setup.

 

[tommyp]

Are you doing central air?

I would maybe put a cast iron ng boiler sized to take care of the addition and the existing.
If your house has duct work already and its in working order, I would add a first co air handler http://www.firstco.com/Products/Multi-Family-Residential-Products/Wall-Closet/EVBQ-(Variable-Speed) as one zone for the existing construction, then add a fphx to run the radiant as another zone, and have a zone for the addition and a zone for the garages floor off of that fphx, both low temp radiant...

Now at this time you can use an indirect water heater but I would not, I would run a heatpump water tank, or a tankless rinnai, etc. I don't like running a boiler sized to heat an entire house just to make hot water, its a huge waste...

Duct work is in working order in the existing house. Well except it needs return ducting and there is limited space to install it.

That makes sense though to just pipe the air handler in for heating the current house. I was figuring on running two zones in the addition having the garage on one and the living space on another zone.

I agree on the tankless for hot water. I am going to keep my electric for now and just convert that over when I get the chance.

Using a fphx would you need a mixing valve as well? How do you regulate heat across the fphx.

Thanks for all the help, greatly appreciated.

 

[dfiler2]

Ah ok. So a tempering valve that would add some hot water from the boiler and mix with the return from the floor.

Something like this would probably work for my setup.

Yes, and you could also have a zone of baseboard connected to the primary loop.

 

[jonjon1]

Duct work is in working order in the existing house. Well except it needs return ducting and there is limited space to install it.

That makes sense though to just pipe the air handler in for heating the current house. I was figuring on running two zones in the addition having the garage on one and the living space on another zone.

I agree on the tankless for hot water. I am going to keep my electric for now and just convert that over when I get the chance.

Using a fphx would you need a mixing valve as well? How do you regulate heat across the fphx.

Thanks for all the help, greatly appreciated.

So if the duct work is good, then I think a hydro coil unit would be a great option.

Heres how it would work...
you make a primary loop from the boiler supply to its return with its own pump.

You use hydroulic separation {either an HS or closely spaced tees} for the hydro coil with its own circulator controlled by the rooms t-stat

Then you do the same for the boiler side of the fphx, with its own circ, except this circ isnt controlled by a thermostat its controlled by a aquastat mounted on the emitter sides supply piping.

Then on the emitter side you run a circ for each low temp zone.

So, if you buy an oversized variable speed first co unit {you can even add a second coil to the duct work above the unit, or if you are not ging to use the a/c remove the a coil and mount the second hydro coil there, the more coil area the lower the temp you will need.} you can get your boiler temp under 150 easily.

Now with the boiler high limit set at 150, the fphx circ only calls in at say 110, it circulates that 150 degree water until the low temp return hits 110 and then stops..

SO NO MIXING VALVES NEEDED... I have much more faith in a low temp fphx than any of the mixing valves currently on the market, especially when coupled with a cast iron boiler and steel circs...


Its how I do all my high end radiant systems where low and high temps are sourced from the same battery...


You won't find a ton of the info on the net, although it is out there, it costs a bit more upfront but in the long run it is more comfortable and reliable...

 

[tommyp]

Thank for this. I am now getting it. Seems like a great plan. I sent you a Pm and I am going to contact a few local plumbers and see what the costs would be to set something like this up.

 

[schultzy]

I put one of these on my detached 2.5 car Garage.

http://www.motherearthnews.com/renewable-energy/solar-air-heater-zmaz06djzraw.aspx

Keeps the Garage 20 degrees warmer than outside on sunny days. I run a little electric oil heater on low or high depending on the temp. Garage is well insulated.

 

[tommyp]

I put one of these on my detached 2.5 car Garage.

http://www.motherearthnews.com/renewable-energy/solar-air-heater-zmaz06djzraw.aspx

Keeps the Garage 20 degrees warmer than outside on sunny days. I run a little electric oil heater on low or high depending on the temp. Garage is well insulated.

I don't really have any good southern exposure on the walls. I was thinking of running some solar collectors on the roof of ether the garage or the house to supplement hot water heating. I am going to have to figure that one out and how to add that in but that will be down the road. I would also like to have some solar pv panels as well for emergency situations. But again just kicking it around and putting stuff in place to make it easier in the future.

 

[tommyp]

Started drawing up the plan. Let me know what you think and where I went wrong. two zones of radiant. Plus the air handler

 

[Jackfre]

I figure that 5% of all the homes and apartments in the State of Vermont have Rinnai Energysaver in them. all your neighbors aren't wrong. Look into them and also the tankless as you note.

 

[Kaizen]

recent this old house show http://www.thisoldhouse.com/toh/tv/video/0,,20909815,00.html scene 6. last week they showed the finished product. you don't need something this complicated but good info

 

[tommyp]

Cool thanks for the links.

Talked to a helpful and knowledgeable plumber last night he is coming out Saturday to check over the current setup and suggest a plan to proceed. He was talking about a condensing Bosch Greenstar boiler instead of a traditional boiler. Said it would work well with the air handler and radiant. Any thoughts on this boiler in the setup that is being discussed?

 

[tommyp]

I figure that 5% of all the homes and apartments in the State of Vermont have Rinnai Energysaver in them. all your neighbors aren't wrong. Look into them and also the tankless as you note.

Thought about just running a direct vent in the house and another in the addition. It is definitely an option. But I think I really want to setup for radiant. I am constantly in the garage working/hanging out in the winter and on the weekends and after work. The garage space is also attached to living space on the same slab that will be continually heated anyway. So I am ok with keeping the garage heated 24/7 instead of a heat as I use. If my habits change in the future I will adjust the heating plan.