Considering a Hydronic Heating System in an old house


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Old 04-22-14, 08:52 PM
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Considering a Hydronic Heating System in an old house

Hello!

First post... allow me to introduce myself. I am an artist/engineer/physicist/fabricator. As an artist I have no money, as an engineer I think I can do anything, as a physicist I have big ideas, and as a fabricator I have a bunch of tools. None of those professions means that I know what I'm doing, however.

My fiancé and I just bought a 4-plex in Los Angeles. I've been working hard on it for the past few months after work and on the weekends. I've successfully swapped out the galvanized plumbing in 2 of the units for PEX, as well as some other piddly maintenance. The main house (where we'll eventually be living) is a huge mess. It needs updated electrical, plumbing, flooring, a redone bathroom and kitchen, etc. As you can imagine, after sinking a bunch of money on the down payment I don't have the tens of thousands it'll take to have it redone professionally. I'm hiring out the electrical work, because I'd rather not burn down my house. But, the rest of it I'm trying to do myself. We're almost finished with the demolition, but honestly that's the easy party. Now it's time to start putting things back together. A big priority is to get the bathroom usable. If we can get the bathroom running we can move in to the house and free up our other unit so we can start to rent it out.

Right now we've taken the bathroom floor completely out. We had water damage and termite damage to repair. But, while most of the plumbing is accessible it makes sense to run the plumbing under the house. This got me thinking about the heating solutions. We're in LA so it doesn't get cold here. But, there are always a few weeks where the heater is on, just to keep the chill at bay. Our gas heater is in a bad spot (only in the living room, no heat for the rest of house) and it's in rough shape. In fact, we might just remove the entire wall that it's in, as it'd improve the flow of the space.

I was thinking of installing baseboard heaters in the livingroom, and each bedroom of the 2 Bd/1 Ba house. I'd run the heaters off of the water heater, which is outside. I figure the kitchen will have its own heat. I'll come up with a rough design soon, but I wanted to get some feedback. Does this heating solution make sense for southern California? Should I use a flat plate heat exchanger to keep the domestic water supply separate, or should I tie the water into the same loop to keep it moving? We won't need heat for 75% of the year, so the water would sit stagnant in the pipes. Is this a problem?

Thanks everyone for taking the time to read my post. I hope to have some drawings/photos etc up soon.
 
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Old 04-23-14, 04:51 AM
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A water heater really isn't designed to heat a house. Do a heat loss calculation to find out how many BTU's you'll need then pick a system based on that.

Have you considered a heat pump?
 
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Old 04-23-14, 09:23 AM
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Tom,

I got the idea for using a water heater as a heating source from the manual for my new hot water heater. They supplied instructions and a diagram on how to set it up. I'm using it as a starting point for the project. Remember that I live in Los Angeles. Our current heater for the house is just a natural gas wall heater in the living room. I think utilizing three baseboard heaters (one in each bedroom and one in the living room) will be plenty to heat the house. It will certainly be more than what the house has right now.

I like heat pumps, but they are larger than I think I need. Most seem to require ducting and an air handler, etc. Unfortunately that will require more retrofitting than I'm ready to tackle with this project.
 
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Old 04-23-14, 10:19 AM
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considering a hydronic heat

There are air to water heat pumps one made by Robur is called an absorption heat pump which doesn't use a compressor but heat, usually natural gas to run the system.
 
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Old 04-23-14, 11:16 AM
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What make and model is the water heater?

Can you provide a link on-line that we can view the installation manual?
 
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Old 04-23-14, 12:07 PM
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I found the hot water heater manual where I was introduced to this idea:

https://www.rheem.com/documents/prof...nd-care-manual page 15

The water heater I have in my house is a 40kBTU/hr model. I'm going to explore the baseboards that I might use and see if this makes sense. I figure that I'll need about as much as a decent electric space heater in each room. 2kW x 3 ~ 20kBTU/hr. That gives me some headroom to take a shower every now and then!

The question is if I should hook it up through a heat exchanger, adding ~300$, or if I can utilize the method of hooking it up through the domestic water like in the manual.

Any thoughts?
 
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Old 04-23-14, 01:08 PM
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The very first thing to know is whether or not the city will even ALLOW the use of a water heater for space heating. Many will not (I'm far from LA and have no clue if they will allow).

Many that do allow will only allow with the stipulation that the water heater is ASME RATED for use as a central heating source and if so the unit will carry the ASME " H " marking indicated that it has been evaluated and is acceptable.

Given that the last time you had a freeze in LA was like 1939, and you have less than 1200 degree days / year, I'm pretty sure that a water heater will meet the heat load, but you want to do what's legal and safe...
 
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Old 04-23-14, 04:22 PM
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What's the source of heat for the other three apartments . . . . if any ?
 
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Old 04-23-14, 09:56 PM
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I'll look into the local codes, good idea.

The other units have one gas wall heater in each. Having one heater is the law here. And there are a few weeks when they're really needed. Homes built in LA tend not to have any insulation either, and it can get surprisingly cold inside without a good heater. It's worth noting that the other 3 units are unattached, were built in different eras, and have independent floor plans, etc.

Work will occupy much of my time for the next few days. Going to have to do some research when I can.

Thanks for all of the help so far. I'm full of dumb questions.
 
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Old 04-24-14, 11:07 AM
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Let us know what you find out from the city...

To answer the original question though...

If you notice in the plans that you cited, there is mention on the diagram to run the pump for a minute every now and then... and this is probably at least partially for the reason of 'stagnant' water in the piping. But what about when you don't want heat? I guess a minute every now and then isn't going to make much difference, but still...

I believe that if I were doing this I would myself use a heat exchanger. I think it means more than a $300 addition though, because not only do you need the heat exchanger, you also need all the acoutrements of any closed heating system; pressure reducing valve, backflow preventer, expansion tank, air removal device, etc...
 
 

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