Heater only runs when filter on recirculate

mcp · Postby **mcp** » Thu 18 Jun, 2009 18:35

We had a technician come and replace the pressure switch on our heater 2 weeks ago. He was back this week when we couldn't get the heater going again. At first it seemed we had gone through another switch but after some fiddling he discovered the heater will run when the filter is set to Recirculate but wont start when set to FIlter.
He's telling me its a filter issue and I need to replace the sand in my filter (or replace the entire filter as its about 10yrs old). Someone else suggested I could replace my pump to up the pressure going thru the filter, and that would help get the heater going.
Anyone heard of this issue before? I'm not sure which is the right path to take.
Thanks

Postby **Denali** » Fri 19 Jun, 2009 01:11

mcp wrote:We had a technician come and replace the pressure switch on our heater 2 weeks ago. He was back this week when we couldn't get the heater going again. At first it seemed we had gone through another switch but after some fiddling he discovered the heater will run when the filter is set to Recirculate but wont start when set to FIlter.
He's telling me its a filter issue and I need to replace the sand in my filter (or replace the entire filter as its about 10yrs old). Someone else suggested I could replace my pump to up the pressure going thru the filter, and that would help get the heater going.
Anyone heard of this issue before? I'm not sure which is the right path to take.
Thanks

I would start with a good backwashing of the filter. This is often all that is needed for the heater to come on. I can see replacing the sand if it been some years since that was done, but replacing the filter doesn't track for me.

mcp · Postby **mcp** » Fri 19 Jun, 2009 07:14

Thanks Denali. I did run a good long backwash (about 20min) but no luck.
I'm not sure when/if the sand was replaced. We've been in the house 3 years and it hasn't been done in that time. Guess that is my next option.

Postby **Me...** » Fri 19 Jun, 2009 07:30

Possibly the pressure switch is not set properly.

You can open up the filter and check the sand bed. Sometimes only the top 6-12 inches need to be changed. It should look like nice sand. If it is hard and crusty or has lots of big lumps in it it needs to be at least partially changed.

mcp · Postby **mcp** » Fri 19 Jun, 2009 12:51

Well I was playing again today. The heater seems to be running on Filter when I have suction from the Vac line, but when it's on the skimmer the heater won't start. There is no obvious change in pressure on my gage when I switch from skimmer to vac line.

Postby **Denali** » Sat 20 Jun, 2009 07:01

mcp wrote:Well I was playing again today. The heater seems to be running on Filter when I have suction from the Vac line, but when it's on the skimmer the heater won't start. There is no obvious change in pressure on my gage when I switch from skimmer to vac line.

There is only one answer here: your heater is possessed! hehe

I would follow the advice in the previous post to check on the condition of the sand. What type of heater do you have BTW? In older heaters sometimes the problem was in the tube (syphon loop) that leads to the pressure switch. A bit of corrosion gets in the tube and higher than normal pressure is needed to activate the pressure switch.

There isn't any reason to replace the filter or upgrade the pump. I assume your system worked at one point so no need to change equipment.

mcp · Postby **mcp** » Mon 22 Jun, 2009 13:44

Denali wrote:There is only one answer here: your heater is possessed! hehe

Ha ha! Totally agree it's possessed!
Thanks for the input. I have someone coming to check the sand on Wednesday.