NEW Mastertemp 400 heater is not heating water

woodywhv

Member
Apr 23, 2017
6
Corpus Christi
Howdy,I have a new Mastertemp 400 unit that I installed as a replacement for the old Sta-Rite Max-E-Therm 333.The unit fires up but does not heat the water.The following happens:- I push SPA button (Temperature is set to 104F), blower activates and 30s later heater fires with a wooopf. Exhaust gets nice and hot so unit is producing heat- Pump is pumping water through the unit, the flow rate of the pump is 60-70 GPM. There is no bypass, all the water is going through the unit as the spa has massive water movement. There is no by-pass installed- No LEDs come on, the only lights on the display are the green SPA light and the yellow heater light- Heater works as it should as far as I can tell, but the water going through it does not get hotThe heater burns and runs, it does not shut off, only when I manually shut it down.Any ideas why the water does not seem to be going through the coils?Any help would be great, thanks!Michael
 

swimcmp

In The Industry
Nov 8, 2011
1,048
Moberly,MO
Not trying to be a smart aleck but are you sure water is going through the heater from inlet to outlet. There is an internal bypass that could be stuck open also.
 

woodywhv

Member
Apr 23, 2017
6
Corpus Christi
Hi, thanks for the comments so far. I am pretty confident that water is entering the manifold abd is coming out the exit side. To verify that I slightly loosened the connection to the salt cell and water is squirting out. Aside from that the spa jets are spurting water at a high rate. If the water is entering the heater coils I cannot say. I had thought of the thermostat being stuck open but ruled it out as this is a new unit. If you think this is a common error I will take the thermostat apart and check for damage or pollution.
Question, is there a valve that is controlled electronically that may be defect? I do not know that these units have one but it mighy be a new addition? I wanted to check all bases before calling customerservice.
Thanks
 

ps0303

TFP Expert
In The Industry
Jul 6, 2011
3,968
FL
How about a picture of your setup? Are you isolating the water in the spa or is this a stand alone spa? If it's firing up, then you have water flow.

You said this is a new heater you installed, why would anyone think the bypass is broken? If the bypass was broken it would have a knocking and banging sound to it. But again, this is a new unit the OP said so I would not suspect that being an issue.
 

GDN

Bronze Supporter
Oct 17, 2016
308
Dallas, TX
Two things - there was a thread here a few months back - it's similar, but also very different - in that thread the user wasn't getting water flow when using the heater and after a few days they discovered that the inlet and outlet were plumbed backwards, but they were getting very little flow because of that valve I believe. Sounds like you say you are getting normal or lots of flow - so doesn't sound the same, but maybe double check something so basic.

The second thing I noticed when looking through the pdf booklet that was referenced in one of the earlier posts - I happened to see this on page 3 -
"NOTICE:Do not use this heater as a heating boiler,water heater, or for heating salt-water pools. This heater is intended for use in heating fresh water swimming pools or spas only".

There are a lot of people on this site that have this heater and I'm sure some number of others are probably salt water as well, but I found it interesting to see that in the booklet as I'd never heard that before.
 

woodywhv

Member
Apr 23, 2017
6
Corpus Christi
The heater is replacing an older STA-RITE unit that plumbs up exactly the same. The plumbing is straightforward in that the spa is divided from the pool by an actuating valve which closes the pool circuit and opens the spa circuit. That works as it should.
The hard part about this problem is that it fires up nicely so the trouble shooting manual does not have a solution or check path to find the fault. The manual is soley to heater will not fire etc....
Does any one know if the manifold has an electrical valve in the new units?
 

ps0303

TFP Expert
In The Industry
Jul 6, 2011
3,968
FL
No electrical valve in the manifold. Please post pictures of your setup. I suspect something is not set right. Seeing this unit is actually the same as your old just in a square enclosure, something else is up.
 

Pool Clown

In The Industry
Sep 5, 2008
1,855
Silicon Valley, CA
I see that this heater is replacing one that was already installed. Did you just move into this house and was informed that the pool needed a heater? If you are a new owner and have not experienced the heater performance, this MAY be a case of over expectation. Forgive me if i am wrong.

That heater can only be expected to raise the temperature of a normal size pool (say 15X30 or 20X40) by only 1 to 2 degrees per HOUR. In the spring time, it would not be unusual to need to run the heater 24 hours or more initially to bring the pool up to temp. If you have a spa, you can expect 1 to 2 degrees heat rise per MINUTE. If you are trying to heat the spa and not getting this kind of performance, is the spa overflowing into the pool during this time? If so, you may have a valve actuator that is malfunctioning, or you have one of two valves set wrong

If you only disconnected the water connections and replaced the heater (no plumbing change) AND the heater is putting out hot exhaust, you are either not letting it run long enough, or in the case of SPA mode, there is a valve actuator not turning (suction side).
 

woodywhv

Member
Apr 23, 2017
6
Corpus Christi
Thanks for the help so far. To answer a few questions, we habe lived in the house the past years and I have experienced the old heater. It took about 25min to heat the spa from around 75 to100F.
I had the new one running for 20min and the temperature went up by 1F. The inbound and outbound on both manifolds is the same I believe? Top pipe in and bottom pipe out. Neither pipes are getting warm. The heater is running fine, no lights no signals, hot air, hot exhaust, no hot water.
Based on what I have read today, no electrical valve in the manifold, no malfunction of the heater and no error signals, still no hot water, can we assume that the heater is ok and something peripheral is not working as supposed to? But what could that be? I did not change the plumbing just removed and replaced units. I will check the actuator valves to see if they are set incorrectly, but as stated above, the spa is receiving water which is flowing over the step into the pool.

Could the unit have any issues, maybe it being "new" but actually having some controlboard problems? Would a damaged board cause this? The manual is full of statements regarding change the board if this, change the board if that.....
 

GDN

Bronze Supporter
Oct 17, 2016
308
Dallas, TX
This is a weird one, just confirmed - top pipe in, bottom pipe out. If that heater is heating and you have water flowing through it - seems impossible you aren't getting hot water into the spa. If the water wasn't flowing through it I'd think it would overheat and shut down. My Mastertemp will heat the spa about 1 degree per minute as noted should be expected and as your old heater did.
 

Pool Clown

In The Industry
Sep 5, 2008
1,855
Silicon Valley, CA
the spa is receiving water which is flowing over the step into the pool.
It is doing that in spa mode? It shouldn't. That is why the water is not heating up. If you are in spa mode and water is flowing from the spa to the pool, that means you are constantly drawing water from the cool pool and sending it to the spa. So you are getting a constant temp into the heater (never gaining any heat)...

...AND you got 1 degree heat rise in 20 min? The Heater is working, pretty well too!

If this isn't the case, you should contact Pentair for factory service. There is some kind of manufacture defect. Although, if the heater is running without tripping the high limit, and you have hot exhaust, the heat MUST be transferring to the water. Otherwise the heater would knock and bang and eventually high limit out, then cycle.
 

woodywhv

Member
Apr 23, 2017
6
Corpus Christi
Ok that sounds like a possibility. The cycle is going to the spa and seemingly flowing over the step into the pool and then going from the pool to the heater and the spa. So I would actually be heating the pool. Now I like the logic to that one. Makes sense. I will check tomorrow if the pool spa actuator is working on the return leg. I only checked the outbound actuator. Thanks so far to all of you for your creative and persistent help. I will post tomorrow if that was the problem.
Good night
 

GDN

Bronze Supporter
Oct 17, 2016
308
Dallas, TX
Even if your spa is flowing over into the pool with the amount of heat this thing puts out it should be heating that spa some before it spills out - it won't register on the panel because it's bringing in the cold water from the pool, but I can promise you - that flow of water you described coming out of the jets in the tub - you put your hand in front of one of them and you'll feel hot water that has been heated.

Have to agree though - if you are spilling over the spill way - you have a valve set wrong and its more like heating the whole pool, but you will feel warm/hot water coming out of that jet in the spa.
 

Pool Clown

In The Industry
Sep 5, 2008
1,855
Silicon Valley, CA
but you will feel warm/hot water coming out of that jet in the spa.
WADR, I dont think so...

You may feel a difference, but it will definitely not be hot. You would feel the difference in heat when the heater first starts to heat. Because the spa would be the same temp as the pool and you would feel the heater differential coming out of the spa return (4 degrees).. Typical heater differential is ~4 degrees, engineered that way to limit condensate. Forced air may be a little more (Jandy Hi-E2). If you are pulling a constant say 70 degrees from the pool, the most you could hope for is 74 by the time it reaches the spa. Spa would get (overall) up to 74 degrees then sort of plateau. That 74 degree water would then need to migrate from the spa spillway all the way to either the main drain (not likely, heat rises), or to the skimmer, where ever that is in relation to the spa, to begin to show an overall heat rise. Not to mention that the 74 degree water is experiencing heat loss, or rather heat absorption from the surrounding pool water the whole way to the skimmer.

If you think about it, if the OP got one degree in 20 minuets, with this scenario, that heater is rocking!
 

CountyBumkin

Bronze Supporter
Apr 3, 2016
58
Orlando FL
My RayPak 400K BTU will heat the spa water enough that you can definitely feel the heat at the jets. Of course not scalding hot, but pretty hot. Maybe I can put a thermometer in the stream and measure for anyone interested.
 

ps0303

TFP Expert
In The Industry
Jul 6, 2011
3,968
FL
I will check the actuator valves to see if they are set incorrectly, but as stated above, the spa is receiving water which is flowing over the step into the pool.
As stated earlier by Pool Clown, you are drawing in cool water from the pool and cycling it thru the spa. Spa will not heat up correctly until you stop that overflow into the pool. You have a valve that is not working correctly.
 

Pool Clown

In The Industry
Sep 5, 2008
1,855
Silicon Valley, CA
I will check tomorrow if the pool spa actuator is working on the return leg. I only checked the outbound actuator. Thanks so far to all of you for your creative and persistent help. I will post tomorrow if that was the problem.
Good night
By "return leg" do you mean water returning to the pump? Because that is the one you want to check (suction side). The actuator in front or closest to the filter pump. The one that controls where the water comes from.

The return (where the water goes), seems to be working. Water is going to the spa, we want to take water from the spa as well.
 

CountryBumkin

Bronze Supporter
Jan 9, 2017
124
Orlando/FL
The second thing I noticed when looking through the pdf booklet that was referenced in one of the earlier posts - I happened to see this on page 3 -
"NOTICE:Do not use this heater as a heating boiler,water heater, or for heating salt-water pools. This heater is intended for use in heating fresh water swimming pools or spas only".

There are a lot of people on this site that have this heater and I'm sure some number of others are probably salt water as well, but I found it interesting to see that in the booklet as I'd never heard that before.
BTW - What we sometimes call salt water pools (i.e. pools with a salt water chlorine generator (SWG)) are still considered to be "fresh water pools" since the salt concentration is less than 6000 parts per million (ppm). The ocean (salt water) is 35 parts per thousand or 35,000 ppm.
 

woodywhv

Member
Apr 23, 2017
6
Corpus Christi
Problem solved!

First of all thanks to everyone for the inputs and suggestions. Special thanks to Pool Clown for catching the Spa overflowing into the pool.

The automatic suction side actuator to the pump was stuck. The actuator going to the pool/spa was cycling correctly. I hadnt watched the other one during operations. So I was indeed drawing from the pool and pushing into the spa.

Enjoyed a 102F spa yesterday thanks to y'all.

Michael
 

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