Hydronic Air Handler - Heat/Hot Water Problem

HVAChick

We have a residential hydronic air handler, Goodman AH2429. When we turned our heat on for the first time two weeks ago, we lost hot water in our taps after a few hours. If we turn our heat off, our hot water returns after an hour or so.



Recent work done:

1. June 2010 - New HVAC heat pump unit installed outside, A/C worked great all summer

2. July 2010 - New well pump holding tank installed (our old one was starting to rust out)

3. August 2010 - Duct cleaning and air handler cleaning

4. September 2010 - Two new elements and two new thermostats replaced in Hot Water Heater (because we thought this was the source of our lack of hot water,before we realized $300 later that it was the air handler).



Our system: Electric hot water heater supplies water to air handler.



So if our HVAC system is turned off, we have plenty of hot water coming from the taps. If we turn our heat on, we have heat for a few hours, but then we start to get ice cold air blowing through vents, and we lose hot water from the taps.



This tells me what? Our blower motor, blower wheel, and thermostat must be working OK if we have heat for a little while, right? What do I need to look at? The return pipe that carries the cooled water back to my water heater? Something that is blocked or just dirty? If the return pipe is blocked or gunked up, where is all that water going? Wouldn't I start to see leakage?



I know I have to call an HVAC professional, but would like some guidance on what possible problems I might have first. I've already dropped a few thousand dollars on the recent work over the past few months, so I want to make sure I understand this system and possible issues before I call someone in here. Thanks in advance!

NRT_Rob

well

if this is on a typical electric hot water heater, you have most likely simply outstripped your water heater's capacity to make heat.



those units aren't very powerful...

HVAChick

Well but no

We replaced our HVAC with the same exact unit and we haven't upgraded anything else that would make our hot water heater unable to keep up the capacity, considering it was all working fine for the past 5 years. None of our systems are past their life expectancy. Something in the air handler or the pipes must be needing repair. Just looking for help.

Ironman

Where Do You Live?

It better be where the temp. never falls below 50deg. Wait, just noticed you have a heat pump. Make that about 40deg. depending on the heat loss of your house.



The heat element in your electric water heater only produces 15,350 Btu/h. Not much to heat with. The Goodman AH2429 has a 29,000 Btu/h coil. The water heater can't keep up with it. This system probably needs a gas water heater.



You could try setting the thermostats on the water heater higher, but you should have an anti- scald valve installed if you do this. You may also want to have the heat pump checked.

NRT_Rob

i don't know what to tell you

if you are getting cold water at the taps, the electric heater is depleted of heat. that is why your AHU is not heating at that point as well. That's a plain fact, this is a heat issue, not a flow issue. If it were a flow issue, the tap water would still be hot because the AHU would not be extracting the heat from the tank in the first place.



why it worked before, I couldn't tell you. it should never have worked. Unless, perhaps, the original installer did something funky like dial back fan speeds significantly? I'm not sure even 'speed 1' would be low enough (it appears that AHU has 3 speeds), but if it's on a higher speed, that would be one thing to try, turn down the fan speed and see.



If this worked at all in the past I would assume you don't have much of a heat load and that the original installer may have hacked the fan speed on the original unit, or cut off AHU usage when the water temperature dropped to a certain level perhaps.

tim smith

RE: water heater and heat pump problem

My guess is there was a wiring mishap when the heat pump or water heater was installed. The heat pump is not heating and therefore relying solely on the water heater for heating. This will NOT work. Electric water heaters just do not have the output to heat most all houses. Also it could be that your heat pump just is not working well. I think most likely a wiring mistake because it was working ok in cooling you said. I would have the heat pump installer come back out and check out the operation. Good luck.

Mark Eatherton

Yeah, SOMETHING has changed...

If it worked decently before, it should again.



Keep your tank hot and avoid exposure to high quantities of Legionairres Disease.



ME

don_9

knowing your system

Sounds more like you have stright ac with a hydronic coil.tap in to the typical not enough capacity water heater.Its also the typical builders pick for a cheap heat plant.

I do not believe you have a heatpump.most of us airhead would not even tie a heatpump into a h2o heater.we would pick electric for our supplement heat.

Call the company back and ask them for a heat loss calc along with a daily domestic hot water load estimates.

Then there is that priority thing like how do i stop the heat from running when i need to take a shower.the people in my area turn the heat off when they want to take a shower with one of these system.never a problem in the summer only in the cold winter.Hmmmm.

Ironman

You May Not Have A Heat Pump

If you can give me the make and model # of the outdoor unit, I can tell you if it's a heat pump or just an air conditioner.

Ironman

Your AHU Is NOT Compatible

The "AH" series AHU were only compatible with 10 & 12 Seer R22 equipment. If a new R410a unit was installed with this AHU, that may explain your problem. You may have already had a failure with the outdoor unit, whether it's a heat pump or straight A/C.



See attachment.

HVAChick

We do have a heat pump

We do have a heat pump. And we do have a hydronic air handler. Not sure why our system is so backwards but it is. And that's why I was hoping y'all could help me. We do live in the Mid-Atlantic which goes way way way below freezing temps in the Winter. We have never had a heating problem in our small home for the past six winters.



My NEW heat pump is a Rheem 1.5 ton 13 Seer with a model # of 13 PJA 18 A01

Ironman

I'm in the Mid Atlantic

What city/ town do you live in? I may be able to help you myself or else know of someone to recommend that you could trust.



Your AHU is not compatible with a 13 Seer, R410a heat pump, but there may just be a minor wiring problem causing the unit not to function in heat. If you could tell me the make and model of your thermostat and if it was replaced with the heat pump, that would help.

HVAChick

Problem Solved

The system works fine. The HVAC/air handler/hot water heater work together just fine, like they always have.



The problem turned out to be the #@$$#@#$ "smart" thermostat my electric company installed. Those new thermostats don't always work with older systems apparantly. The old thermostat was reinstalled and all systems are working beautifully.

Ironman

The Thermostat...

Was probably setup wrong. Many of the new stats are made for conventional or heat pump application. The installer has to do the setup programing to configure the stat to match the the system. This may not have been done correctly, if at all.



Also, Rheem energizes the reversing valve in heating through the "B" terminal. Every other manufacturer energizes the valve in cooling through the "O" terminal. This is part of the stat setup programming.



I checked Rheem's specs. for your heat pump and it is an R22 unit, so you should be OK with it connected to the old AHU.



Glad you got it fixed.

ShawnLayne

Hydronics frustration

I have a 10 year old home with 2 furnaces and 2 60g gas water heaters. When I turn one of the 2 furnaces on, I lose hot water at all taps within a couple minutes. Also, the furnace struggles to keep the house up to temp. It mostly blows cool air. Both water heaters are tied together in a series. I've been told they are in a "closed system". I've had plumbers and HVAC guys out multiple times and nobody can fix it. It seems to me that something has to be wrong with the one furnace/air handler because not only does it blow cold air, but it prevents the faucets from getting hot water. The instant I shut this unit off, I have an endless amount of hot water. Just seems like a simple valve not opening/closing to me. I'm to the point I just want to buy an entire new system because nobody can give me a straight answer.

Techman

HP Problem?

The electric hot water heater supplies hot water for both domestic/potable water and the hydronic coils? 06:50 ,just noticed the OP date, late again!

Harvey Ramer

Well

Make and model # of all equipment. Airhandler, heatpump/AC, gas water heater?



If it is a natural draft conventional gas water heater. It's just not going to work. Sorry.



Harvey

ShawnLayne

Hydronics Frustration

The 2 60g water heaters are Bradford White.  They are both gas.  The air handler only has Grenada, MS on it.  I think the company is ADP.  There isn't another single marking on the thing to tell me what the model is though.   The one that controls the downstairs is quite a bit bigger than the upstairs one, but they are both the same mfgr.  They are both electric.  The outdoor heat pumps are both Armstrong.  The Thermostats are White Rodgers.

ShawnLayne

Hydronics Frustration

The 2 60g water heaters are Bradford White.  They are both gas.  The air handler only has Grenada, MS on it.  I think the company is ADP.  There isn't another single marking on the thing to tell me what the model is though.   The one that controls the downstairs is quite a bit bigger than the upstairs one, but they are both the same mfgr.  They are both electric.  The outdoor heat pumps are both Armstrong.  The Thermostats are White Rodgers.

Squid1622

So I have a weird problem with my system. I have a hot water heater hooked to one of these hydronic air handlers. The hot water heater is a brand new 50 gallon tank with 65000 btu's. When the air handler is running, I get hot air and hot water, but when the handler is not running I do not get hot water. The old hot water heater had roughly the same specs (I think it was 50,000 btu's) and it didn't have an issue supplying hot water (until it started leaking and had to be replaced). What is going wrong with my system.

JUGHNE

Did the problem start with the new water heater? Sounds like a piping/plumbing/zone valve/pump issue. How about pictures of the water heater and air handler showing all piping near and between each.