Radiant, Baseboard & domestic all in one?

bigblock10

I'm looking into the possibility of combining my heating systems into one unit. ( I will not be doing the install myself ) but would like to know if it possible before i start looking for a heating professional.

I have a 1,500 S.F tri level house with a 70,000 BTU propane baseboard fin heat in the lowest level and the top level. The main level has stand alone electric hydronic radiant in floor heat ( a remodel was done and they removed the baseboard fin type heaters)

I also have a electric 50 gallon water heater for domestic hot water.

My question is. Is there a unit out there that i could have installed that could combine all of these into one unit? It would be nice to free up some of the electrical that the hot water heater and radiant system are using and get them running off of propane.

attached is a picture of the boiler and the radiant setup.

Thank you !

Paul Pollets

You could use a Viessmann 222F combi model and add the mixing valve kit for the radiant temps. The unit will convert to propane by adjusting the codes, (no gas valve conversion required) and has a 28g SS water tank within.

Jamie Hall

Other than the perhaps minor point that you will have to reinstall the hot water baseboards on the main floor...

You can. Run the heating with the boiler, and also use it to heat an indirect.

GroundUp

Jamie Hall said:

Other than the perhaps minor point that you will have to reinstall the hot water baseboards on the main floor...

You can. Run the heating with the boiler, and also use it to heat an indirect.

Why would he have to reinstall the BB when the space is already heated via radiant floor? It's as simple as adding a mixing device to the LP boiler system and ditching that POS electric tankless posing as a boiler.

hot_rod

Start with a heat load on the home, I'd expect to see something around 30,000 BTU/hr or less if the home is sealed and insulated.

Then see how much fin tube you have and how low of a temperature you could run it and meet the load.

A combi boiler with a two temperature heat piping would probably work well. Possibly a small buffer tank or a large volume boiler like the Viessmann 300 to prevent short cycling.

A 100 or 150 combi may work depending on your DHW loads. The boiler needs to size to the largest load, in many cases that is the DHW in a small home.

A 110- 120,000 combi should provide 2- 2.5 gpm of endless DHW. Lock the heating side output to 30,000 or whatever the load calc shows.

A combi would take up about a 3X3' wall space, maybe 12" deep.

A space saver water softener would also buy some floor space, the softening tank is inside the brine tank for an 18- 24" diameter footprint.

Zman

What kind of maniac installed the electric boiler? They did all the labor that would have been required to upgrade the whole system but left the old boiler in place.
Either a combi boiler or condensing boiler with an indirect would be a good solution. The combi would take up less space and cost a bit less. The disadvantage would be that it would be oversized for the heating load causing it to short cycle.
What are your domestic water needs?
How is the radiant installed? Under the floor with aluminum plates?

hot_rod

Zman said:

What kind of maniac installed the electric boiler? They did all the labor that would have been required to upgrade the whole system but left the old boiler in place.
Either a combi boiler or condensing boiler with an indirect would be a good solution. The combi would take up less space and cost a bit less. The disadvantage would be that it would be oversized for the heating load causing it to short cycle.
What are your domestic water needs?
How is the radiant installed? Under the floor with aluminum plates?

Really the short cycling with a combi in no different than the cycling with a mod con boiler only?

Depending on the brand and model, most all can be locked down in heating mode, down to the lowest setting, typically around 8 k. on a 120K combi.

Ramp delay, max. output limit, ODR all add up to great ways to all but eliminate short cycling.
Only if the smallest single zone is is lower than the turndown of locked in firing rate would you expect see any shortcycling.

The efficiency actually increases a bit when you lock them at low firing rates as you expose a large HX to a small burner rate and you get more condensation. Assuming you are running those temperatures.

Viessmann has some excellent graphs showing low firing rate performance and efficiencies gains.