Split single zone house - DIY

I have a decent sized two story house that is all one heating zone. I really want to improve the comfort of certain areas and if there is some energy savings that would be great.

My system is baseboard hot water and has a single thermostat in the dining room that controls the whole house. All of the piping to and from the baseboard radiators was replaced a few years ago with pex (previous owners). There are 4 loops, one to each area I want to zone but they don't split off all together in one spot like a manifold. There is a larger copper pipe that crosses the whole basement and there are four Ts. At each T it changes to pex and has a shutoff valve and is the beginning of a loop. It's like a manifold that is stretched across the whole basement. On the other side of the basement its the opposite. A large copper pipe with four Ts and all of the returns. It seems like it's perfect for adding zone valves except the valves would be spread across the basement instead of all in one nice neat location.

I have an oil fired boiler that also does domestic hot water. Controlled by a hydrostat 3150.

Here are my questions:

This seems strait forward, is this a good DIY project?

Does it matter that the zone valves would be in different locations across the basement?

I was looking at a Taco ZVC406-4, good choice?

What's the best zone valve for the job, Taco, Honeywell?

Does it matter if the valves are on the supply side or the return? Return would be easier in my situation.

Having never worked with pex myself what the best way to attach the zone valves inline with the pex?

And finally is there anything I'm not thinking of?

 

Anyone have any thoughts?

 

I don't know how/why I missed this ?

Doesn't seem out of the realm of a DIY homeowner with reasonable skill level.

No, not at all.

I like them. I hate what I call "rat's nest" wiring, but it works just as well, and CAN be done neatly if one takes care to do so.

They're all equal as far as I'm concerned.

Not really. If return is easier then return it is.

It would be nice to find a zone valve that has the PEX terminations... but I don't think you will. I've never seen them unless they are on a manifold for radiant heating.

You'll need to use adapters. You'll need the proper tools to terminate whatever tubing you are using.

Probably... and probably me too.

Let me ask a few questions:

How many fee of baseboard on the largest zone?

How many feet of baseboard on the smallest zone? Just the fin tube element itself, not any of the connecting tubing.

Can you tell what size the copper is?

What size is the PEX tubing?

Did they use the correct tubing? i.e. OXYGEN BARRIER tubing made specifically for hydronic heating.

 

I think I can classify myself as reasonable skill level.

I don't mind paying a little extra for the Taco ZVC406-4 if it's a cleaner installation. A rats nest would drive me crazy.

Largest zone would be 68 feet and the smallest would be 24 feet.

Copper is 1.5 inch and pex is 3/4. They used Wirsbo hePEX Plus which I believe is the correct material.

 

It all sounds good...

The only possible issue I can think of would be if the shorty zones are calling for heat by themselves, it would probably short cycle the boiler.

What make/model and btu size is the boiler?

 

Williamson OWT-5 series 2
Not sure about the BTU. From the label it's either 175,000 or 145,000 based on the GPH but I'm not sure about my GPH.

I've been told it's an overkill for my house but it was put in by the previous owner two years before a complete remodel of the house making it much more efficient.

 

If it's firing at 145K it's probably big enough for a 4000 sq ft home. How many sq ft is your home?

This may be the reason that the system is NOT currently zoned... at least when a heat call comes in there is some 'heat load' for it to work into.

When one of those small zones calls by itself, it will short cycle.

 

Well under 4000, closer to 2500. I assume that's why I burn through oil like they're giving it away.

It supplies my hot water too does that change the calculation at all?

Is there a point at which I'm so oversized that it's cost effective to replace?

 

Do you have a feel for how many gallons a year you are using?

How so does it supply hot water? Is there a 'thankless' coil in the boiler? or do you have an 'indirect water heater'?

The coils in the boiler are VERY inefficient. Like leaving your car idling in the driveway in case you want to run out for a donut after dinner. Keeping boiler warm 24/7 in order to supply a few gallons of hot water a day is very wasteful.

Indirect water heaters are efficient and worthwhile.

I'm sure there is... but not sure how we can find that breakpoint.

I can use my home as an example though. 2000 sq ft give or take... when I moved in in 1984 the boiler was replaced just prior with a 140K unit. I was burning almost 1500 gallons a year.

The house was VERY poorly built. The second floor was a nightmare of heat loss. Oil was relatively cheap, we lived with it for 11 years.

In '95 we demolished the second floor, rebuilt nice tight well insulated construction. Also that year I ripped out all the sheetrock downstairs and insulated. Oil use dropped about 500 gallons the following winter.

We lived with the boiler until 2 years ago when I replaced with an MPO-84 boiler. The past couple years I've burned about 750 gallons with the new boiler.

So, let's say your home isn't the heat guzzler that mine was and perhaps reasonably well built and insulated, like the '95 version of my home. It might be theoretically possible for you to save 25% as I have... BUT, your mileage may vary! You would have to do some cost analysis to determine if it makes sense for you. It was a no-brainer for me because I didn't have to pay the $10K to have a new system installed. Mine has practically paid for itself already.

There's things you can do for little to no money that will help.

I believe you said that you have fin tube baseboard? Are the fins spic and span free of dust, pet hair, etc? You would be surprised how much heat even a thin layer of dust will hold back, forcing the boiler to run longer and waste fuel.

Air infiltration is a bigger heat loss than insulation believe it or not. Any sealing of air leakage into the home that you can do will incrementally lower the heat loss.

Attic insulation is often a DIY-able project. Increasing attic insulation to R40 is a good start... and spending money on having the walls insulated if they are not already is a better investment than a new boiler. It's fuel you only pay for once.

Surprisingly, unless the windows and doors are falling out of the frames, investing in new ones is often the longest 'payback' item on the list, regardless of what the salesmen tell you. It should be the LAST thing you put on your list.

 

Hot water is tankless. I know it's terribly inefficient. I'll have to look back and find out how much oil I was using but 1500 wouldn't surprise me, but I just moved in a year ago and it was a bad winter.

My house has fully insulated walls a fresh 10 inches of insulation added on top of existing in the attic. All windows are new and I had people come in and do spray foam and a blower door test. It's a tight house. Also I vacuumed the fins last winter.

So the summarized version is my boiler is way too big to zone my house as I was planning, four zones. If I only did two zones instead of four could the runs be long enough for zoning? One run would be 60+ feet and the other would be 90+ feet.

Also probably not worth replacing the boiler since I might only get a 25% improvement and since it's three years old.

But it might be worth adding a indirect water heater so I can completely shut down the boiler in the non-heating season. Any recommendations in that area?

Do I have it generally correct?

 

Any thoughts on my summary?

 

This would probably be a better choice. I guess you could try it and see what happens. Might still be light loads for the boiler... the 60 ft zone is probably under 40K BTUH and the 90 is probably under 60K BTUH. You can see that any way you slice it it's not much load... but then, I wouldn't be surprised if the entire home is short cycling the boiler now!

I could suggest some serious reconfiguration of your system... but think $$$. It would include a big buffer tank... think 'battery'... this tank would have FOUR ports, two from which you would draw the heated water for the zones and two to and from the boiler. You could then set the boiler up to 'recharge' the tank. Instead of the zones calling the boiler to fire, the TANK would call the boiler. With a big enough tank you would be able to get several heat calls from the zones without firing the boiler. When the tank cooled to where it needed heat, it would call the boiler and the boiler runs would be long enough to eliminate the short cycling.

You could go a couple steps further even... a constant circulation system that only moves the temperature water needed to replace the heat loss.

But that's a pretty extreme approach. Do-able, but extreme.

Twenty five (theoretical) percent is nothing to p'shaw, but yeah, a three year old boiler is too young to scrap.

If you're burning say 1000 gallons a year, 25% is like $1000 or so... and oil won't get cheaper!

Yes... strongly consider doing the indirect tank FIRST and converting the boiler to 'cold start'. See how that goes and if it's all positive (it will be) THEN think about other strategies for the zoning. Just make sure that the installer you select understands that he will have to convert the boiler to cold start (many haven't a clue about this) and that whatever tank is installed is PROPERLY installed with HEAT TRAPS on the piping to minimize any standby loss from the water tank.

I wouldn't be surprised if going with the indirect tank would save you a bundle of fuel each year. It might cost say $2000 to have it installed. Could 'pay for itself' in a few years, and the fact that you have hot water you can actually count on to be hot when you want it to would be a big plus.

In other words, hit your highest 'waste' items first, and incrementally work your way down the line.

 

67 ft of element is the max recommended. Not pipe length,,


You will not shut the boiler down. But you will make it cold start, and that will save fuel..

May be better off installing an electric heater though... Depends on your electric rates in PA... Do you know this?

 

He might be talking element length... not sure.

But, that 90' would be on two separate zones running in parallel fed from 1-1/2" main.

From post #4:

But you could. I do.

That's a good thought too! With oil prices where they are now, it's very close to being 'even steven' between oil fired indirect and electric, here in NJ at least.

 

My length measurements were finned feet not pipe length. The pipe length would be much much longer. Does that make a difference in the zoning options? NJ Trooper was your recommendation of not doing four zones based on my measurements being the entire loop?

I'll find an electric bill and get the rates.

With the "battery" system being so expensive how would it compare to replacing with a properly sized boiler? Is there an efficiency increase in the "battery" system compared to a properly sized boiler?

 

No, I presumed that you were counting the element itself and not the pipe.

I imagine that the installation price of a large buffer tank and the associated controls would be pretty close to a new boiler. Finding an installer that understands what I was talking about would be next to impossible. You wouldn't get a well engineered system in all likelihood.

I don't know how prices are in PA but here in NJ a boiler replacement would not be less than $7K and often go as high as $10K (or more). (I was quoted $10K when I was feeling old and lazy with a bad back and didn't want to do my own install. Being the cheapazz that I am I stocked up on Aleve and went to town and saved myself about $7K)

So, my system has nearly paid for itself in 2 heating seasons, but if you have to pay an installer, multiply that by about 5.

 

Well out of all the options it seems like I should not bother zoning as it might cause short cycling if I don't already have that problem. Boiler replacement and/or reconfiguring would be $$$ and possibly a 10 year payoff. And with a basically new boiler seems like a waste. Replacing the hot water system with either oil or electric separate heater depending on electric rate would let me change to a cold start boiler and save some money. Any idea on the improvements from my current setup to a cold start? Also is there a magic number of electric rate or a good formula to make the call on oil vs electric?