Separate heat and hot water systems for two apartments

Hi, I have a house in Gowanus & would like to get mechanicals out of the cellar. This is a 2 family house and I am considering having separate heat and hot water for each apartment, with mechanicals residing in each apartment. Building currently has gas boiler & water heater in cellar. I am familiar with the standard gas fired steam boiler & gas water heater w/large tank, but know nothing about other options. As far as changing to separate systems (I have checked old postings in the forum) I am super confused about how separate systems work & options. We are considering a gut reno, but would like to avoid if possible. What is the least expensive system (in installation & material costs) that will give us separate mechanicals? What is the most cost efficient & low maintenance system? Thanks!

makainyc

in Heating 10 years and 2 months ago

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workisfun | 10 years and 2 months ago

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we are in the early stages of renovating the ground floor of our duplex after devastating water damage when we moved in last year. if we decide to redo the slab, we will embed pex for radiant for that level, and plan to staple-up between the joists to heat the upper level of the duplex. i am on the hunt for reliable and knowledgeable heating contractors, who don’t mind teaching me as we go, to guide me through it. if you have any tips or recs, they are much appreciated. i’ve been scouring the web and getting quite an education on radiant heating.

Lurker | 10 years and 2 months ago

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We did a combination of heating types, including underfloor radiant using heat panels.

workisfun | 10 years and 2 months ago

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lurker – did you do radiant? i would love to learn more! thanks.

Lurker | 10 years and 2 months ago

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As someone who just went through a version of this, I don’t see how you’d see any benefit in having two boilers and heating systems in either the short or long term. The pros above will certainly have better info, but supposedly the life span of a high efficiency boiler is 10-15 years, so even if you can get one small enough to heat an apartment without being too big, they savings of having it as a separate system will never be paid off before you have to pony up for a new boiler. If you have a clean and functioning steam system you might want to keep it, as all the other options would seemingly mean gutting. And then look for efficient hot water options like an indirect water tank. If you go all-in and gut, get a new high efficiency boiler, a large indirect water heater (which is really a storage tank), and if you gut consider in/underfloor radiant heating–it’s pricey but efficient and comfortable. Count on 20-30 if you do it right and have permits. But as said above, you’ll see the most benefit tightening your building envelope. Oh, and look at a year or so of planning, permits, and finally building for a gut, if you’re lucky 😉

makainyc | 10 years and 2 months ago

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Hi, Thanks everyone for the super helpful information. A lot for us to consider. As far as the cost for two HE boilers, am I looking at 60K… more? And can I justify this cost by convincing myself that this system will be better for the environment? Thanks!

workisfun | 10 years and 2 months ago

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regarding sizing, some of the tankless combination boilers self-regulate, like my navien. so it won’t expend more energy than necessary.

ellenlourie | 10 years and 2 months ago

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The new high efficiency units are fairly small and can support the entire building load, in fact it’s better to load it up so that it doesn’t short cycle and operate like a standard efficiency boiler. Price wise the installation would be very expensive, think about a price for a properly installed high efficiency boiler x 2\. A properly designed and installed high efficiency boiler can save you a lot on your heating bills but if you install one for you and one for your tenants then you are giving your savings to your tenants and paying many thousands to provide them with that luxury. We have seen so many apartments that have their individual units and the biggest problem is the sizing. There are only a few boilers on the market that are small enough to handle the minimum load for an apartment. Also you have to consider maintenance, right now you are going to save space but you will need to maintain two boilers instead of one. If they are installed the same way at the same time then the wear and tear will be the same as well. So you will need to replace two parts instead of one.

workisfun | 10 years and 2 months ago

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how about a tankless wall hung hydronic boiler that delivers heat and hot water? they take up very little space. you will have to run dedicated pex loops to radiators for each system. but, the space savings without a tank is great. i currently have renters on the top floor of my 2-family. they have one for their unit. i have another for my duplex. we each pay our own gas and electric. we pay all water, but renters pay to heat their water. check out navien ncb series. i preferred them to rheem, rennai, triangle tube, bosch, etc.

steam_man | 10 years and 2 months ago

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Well makainyc it seems like you have 3 options none of which will be cheap. Option 1: Install a high efficiency hydronic boiler and storage tank on each floor. This will mean moving utilities (gas, water, electric and vent) up to each floor plus losing floor space. Expensive and permanently intrusive. Option 2: Insulate the heck out of your walls and install good windows. From there you could install a heat pump system (thus gaining you AC as well as heat). Condensers can go either on the roof or yard. Option 3: Install wall hung high efficiency boilers in your basement with hot water storage tanks. Hopefully your flood line is not too high and you can install the boilers above the flood line. As for the storage tanks…there are a couple of options for extremely durable tanks that can be installed smartly so as to be able to deal with flooding. Feel free to reach out to us if you have any questions. I am making it sound very simple here. For sure there is more involved. You can find our company info in the Brownstoner Local Pros. Molten Mechanical & Metal Works, Ltd.

eman134 | 10 years and 2 months ago

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You will have to convert to hydronic (hot water heat ) to make this work. That means installing a new heating loop in each unit connected to a new boiler. If you can afford the front end costs you should go with an HE boiler (high efficiency) which will pay for itself over the long run.But this is not a cheap date….my contact info is in my profile…heating is what I do