Question about Hayward 250kbtu Ng Pool Heater - Inground

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What is a limit string error locking out the heater on a hayward 250 universal heater???

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The limit string or saftey circut as it was called for years till it wasen't confusing any more is simpley the itims the heater goes through to be shure it is safe to light. This starts with the presure switch and is most often the fault. If you don't have enough water pressure than the heater won't fire. Check your baskets, filter and pump impeller. Then the high limits but these fail for the same reasons. Your thermostat is the next thing in line and the temp sensor or thermistor. (more new names) and on some models their was a flame roll out switch in the bottom front of cabnet. Your problem will be in one or more of these itims and you can usually check them by simpley jumping them with a small wire. But they do a job so do not leave the wire in place to make it work. Good luck.

Posted on Dec 10, 2009

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Our hayward heater H250 model was installed last year.. this year it started up after the winter no problem. We put it on Standby mode while the poolliner was being replaced and not it will not come on.....


Thank you for posting your question here on Fixya.com.


A 'LO' error code for a Hayward heater is a limit string open error. If the limit string opens the heater shuts down and goes into lockout. Automatic restart is 2 minutes after the error condition is corrected and the limit string closes.


The limit string is a series of switches designed to turn off the heater if air or water temperatures exceed a safe operating limit.


The problem may be faulty a switch(es) but is far more likely to be a system condition the switches are reacting too that needs to be corrected. Low flow of combustion air due to obstructions around the heater or the vent; low flow of water through the heater allowing too high a water temp; Poor venting or sooted-over heat exchanger causing flame rollout; inlet and outlet hose connections reversed; these are all conditions that should be eliminated if they exist.


If you are not familiar with these switches or the conditions described you may want to consider calling in a professional. Hayward can refer you to someone in your area who is. Call Hayward at 908-351-5400 or try the website locator found here. It is likely to still be covered under warranty.


If this answer does not fix your problem, please comment with additional details prior to rating the answer. You may also contact me thru our website at www.arrowpools.net. Positive feedback is appreciated once your problem is solved!


John

Jun 08, 2011 | Hayward 250kbtu Ng Pool Heater - Inground

2 Answers

Gives a "LO" and will


Thank you for posting your question here on Fixya.com.


A 'LO' error code for a Hayward heater is a limit string open error. If the limit string opens the heater shuts down and goes into lockout. Automatic restart is 2 minutes after the error condition is corrected and the limit string closes.


The limit string is a series of switches designed to turn off the heater if air or water temperatures exceed a safe operating limit.


The problem may be faulty a switch(es) but is far more likely to be a system condition the switches are reacting too that needs to be corrected. Low flow of combustion air due to obstructions around the heater or the vent; low flow of water through the heater allowing too high a water temp; Poor venting or sooted-over heat exchanger causing flame rollout. These are all conditions that should be eliminated if they exist.


If you are not familiar with these switches or the conditions described you may want to consider calling in a professional. Hayward can refer you to someone in your area who is. Call Hayward at 908-351-5400 or try the website locator found here.


If this answer does not fix your problem, please comment with additional details prior to rating the answer. You may also contact me thru our website at www.arrowpools.net. Positive feedback is appreciated once your problem is solved!


John

Jun 02, 2011 | Hayward 400fdn Low Nox Nat Gas Swimming...

1 Answer

Lo error showing and it kicks off about every 6 minutes


Thank you for posting your question here on Fixya.com.


A 'LO' error code for a Hayward heater is a limit string open error. If the limit string opens the heater shuts down and goes into lockout. Automatic restart is 2 minutes after the error condition is corrected and the limit string closes.


The limit string is a series of switches designed to turn off the heater if air or water temperatures exceed a safe operating limit.


The problem may be faulty a switch(es) but is far more likely to be a system condition the switches are reacting too that needs to be corrected. Low flow of combustion air due to obstructions around the heater or the vent; low flow of water through the heater allowing too high a water temp; Poor venting or sooted-over heat exchanger causing flame rollout. These are all conditions that should be eliminated if they exist.


If you are not familiar with these switches or the conditions described you may want to consider calling in a professional. Hayward can refer you to someone in your area who is. Call Hayward at 908-351-5400 or try the website locator found here.


If this answer does not fix your problem, please comment with additional details prior to rating the answer. You may also contact me thru our website at www.arrowpools.net. Positive feedback is appreciated once your problem is solved!


John

Mar 23, 2011 | Hayward H Series Pool & Spa Heater 400k...

1 Answer

HOW DO YOU CORRECT ''LO'' ERROR (LIMIT STRING PROBLEM) ON A HAYWARD HEATER H250FD??


You need to find out what is bad in the string. The first thing to check is the pressure switch. Not so much the switch but clean the filter and baskets and check the impeller for a clog. These will let the pre sw shut the heater down. The second thing to check is the roll out switch. This is in the bottom of the cabinet on the fire wall just above the burners. It looks like a black sleeve on the wire that crosses the cabinet. It's a wax switch that melts and shuts the heater down if the fire rolls out the front of the heater. If this has gone bad you will need to find the reason it did and fix that or it will just do it again.
The other things on the string you just need to jump past and check, then replace the bad component. Good luck.

Sep 06, 2010 | Hayward 250kbtu Ng Pool Heater - Inground

1 Answer

Our Hayward gas heater keeps giving us a H5 error code and then shuts off. What does this mean?


Could the Error code be HS? That is high temperature limit. Perhaps you' don't have enough flow, allowing the heater to heat the water to a temperature higher, than the thermostat setting. Make sure your bypass valve is closed, allowing full flow through the heater. Check your filter pressure differential , and skimmer baskets.
You didn't give your model number, and there are many models. You can go the Hayward website below and select your exact model number and download the manual. The manual will explain each error code.
http://www.haywardnet.com/inground/products/manuals.cfm

Jul 05, 2010 | Hayward Pool & Spa

1 Answer

CE error code on hayward pool heater


CE= Communication Error between Control Module
and Display Interface Assembly
1. Disconnect and then reconnect power to heater.
2. Check for faulty wiring or connection.
Inspect Display Interface Wiring. Ensure Display Interface Plug is securely attached to Control Module. .
3. Control Module and/or Display Interface Assembly
are defective.Replace Control Module and/or Display Interface Assembly.
Here is a linkt oH aywardmanuals:
http://www.haywardnet.com/inground/products/manuals.cfm

Jul 04, 2010 | Hayward 250kbtu Ng Pool Heater - Inground

1 Answer

Flashing LO


"LO" means a "Limit string open error" has occurred. See the owners manual for the many causes and possible solutions. Owners manual found here. http://www.haywardnet.com/products/Manuals/pdfs/Manual225.pdf

Apr 08, 2010 | Hayward 350K BTU H SERIES HEATER DRAFT...

2 Answers

My hayward heater gives a LO error when trying to heat. you cant put the heater either in pool or spa mode, then set the temp. The temp flashes then you get a LO error. I've checked the valve settings to...


One of your limits is not working or not wired up. An easy way to check the limits - Water pressure switch, Hi limits, air pressure switch all of which have 2 wires going to them. Unplug one item and connect the 2 wires together ( paper clip works fine ) Then retest, if problem does not go away remove paper clip and reconnect wires and move to the next limit. The limits are located in the black plastic header. Always make sure water is flowing through the heater at all times while checking the limits.

Feb 15, 2010 | Hayward H Series Pool & Spa Heater 400k...

1 Answer

Hayward 250 heater won't fire up


Check the control circuit, specifically the pressure switch, for continuity with an ohm meter....any reading over 2 ohms needs to be investigated

Jun 27, 2009 | Hayward H Series Millivolt 250,000 Btu...

1 Answer

Hayward H250K gas pool heater error code


Low Flow errors are not necessarily real. They can be caused by improper adjustment or a defect of the pressure switch. Locate the pressure switch. Verify that the "switch" makes contact. Adjust the dial, reducing the distance the switch has to travel to engage. This will effectively lower the operating pressure required to operate. Keep adjusting until the unit stays on.

May 27, 2009 | Hayward 250kbtu Ng Pool Heater - Inground

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