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Doc Mark · 08-05-2013, 05:30 AM

Got no responses over at the RV Systems & Appliances section so I will try it here!

Here's the situation. The diesel burner has just shut off, but the pump(s) are still circulating the heated anti-freeze. Normally the sound of the pump remains constant, but lately I have noticed it cycles - higher, lower higher lower etc. and when it finally shuts off it sounds as if it just dies away, not a clean stop.

Also, I was standing outside today when the pumps were running and it sounds like the bearings are grinding - a noise I haven't heard before either.

What pump(s) am I hearing? Can I tell by sound the difference between the stir pump and a recirculating pump?

My dilemma is I am 3+ hours away from the closest repair facility and I want to do as much troubleshooting as I can and hopefully have parts on order and in hand before I pull up stakes and drive for 3 hours. Do I need to have them order a new pump? And if so which (there are 3 - 2 circulation pumps and a stir pump).

DW has made it abundantly clear that no hot water is a No Go!

Mark

redbaron73 · 08-05-2013, 05:52 AM

Are you sure it is not the fresh water pump?

Steve Ownby · 08-05-2013, 06:01 AM

Quote:

Originally Posted by Doc Mark

Got no responses over at the RV Systems & Appliances section so I will try it here!

Here's the situation. The diesel burner has just shut off, but the pump(s) are still circulating the heated anti-freeze. Normally the sound of the pump remains constant, but lately I have noticed it cycles - higher, lower higher lower etc. and when it finally shuts off it sounds as if it just dies away, not a clean stop.

Also, I was standing outside today when the pumps were running and it sounds like the bearings are grinding - a noise I haven't heard before either.

What pump(s) am I hearing? Can I tell by sound the difference between the stir pump and a recirculating pump?

My dilemma is I am 3+ hours away from the closest repair facility and I want to do as much troubleshooting as I can and hopefully have parts on order and in hand before I pull up stakes and drive for 3 hours. Do I need to have them order a new pump? And if so which (there are 3 - 2 circulation pumps and a stir pump).

DW has made it abundantly clear that no hot water is a No Go!

Mark

I've read through your post several times and I'm not sure I understand the sequence of events and what you might be hearing. Is this a sound you hear for 2-3 minutes after the burner shuts down and not any other time? If so you are hearing the blower motor that is behind the burner and is running for a couple of minutes after burner shut down to purge the combustion chamber. This blower should run for 2-3 minutes and then shut down cleanly. If it is having trouble shutting down and is making new sounds and running longer then that is the first sign of the electronic control box going bad ( silver box clipped to side of blower housing). That is a $700 experience. If this is your problem post back & I'll look up the web site of a company that sells rebuilt boxes on an exchange basis that appear to work as new.

The stir pump is just one of the circulation pumps and they all should be very quite in operation. They are almost impossible to hear unless you have the main box open & are close to the pump.

It would be worth your time to join this forum:

http://forum.rvhydronicheaterrepair.com/activity.php

This is run by the top AquaHot tech in the country. He answers questions for free.

Doc Mark · 08-05-2013, 06:07 AM

Redbaron73 - no, it is definitely not the fresh water pump.

Steve Owenby - it may well be as you say - your description is exactly what I am hearing, I did not know about the blower motor.

Mark

Steve Ownby · 08-05-2013, 06:27 AM

Quote:

Originally Posted by Doc Mark

Redbaron73 - no, it is definitely not the fresh water pump.

Steve Owenby - it may well be as you say - your description is exactly what I am hearing, I did not know about the blower motor.

Mark

Here is a co who rebuilds the control box. The feedback I have gotten indicates that they work fine & are a huge cost savings:

http://frerichselectronics.com/

If this is your problem, it will continue to get worse until it won't shut down unless you remove power. It's also very hard on the blower motor. The replacement is a simple plug and play. There are two wiring harnesses that plug into the box and it clips to the side of the blower with a spring clip. The clip is very strong & in clipping the box is the hardest part of the replacement.