I have a Weil-McLain CV-4 Gold series 1 bought in 1990. Last week I was oiling the blower motor as PM and then noticed the relief valve leaking. figured the expansion tank was bad so stupidly, I took the old tank off with the top cover off and the tank fell on the control module and also got it wet.
I got a new control module due to the boiler not starting (just power light on)
When I started the boiler it ran for 1/2 min then went to purge and restarted again. This happened over and over again.
I unscewed the pressure valve and laid it horizontal and the boiler then started and ran normally. Would a bad pressure valve work horizontal and not vertical?
If not the pressure valve being bad, what else could be the cause of the system not remaining on?

PS I have the high limit set at 195-200

First, welcome to the pool. I think you will find that the pool memebers can give you good answers to your questions.

Even with my 40 plus years servicing heating equipment and being a certified to service Weil-McLain hydronic heating systems, I would be a fool to give you any advice and you should be a fool to take it.

These can be dangerous systems to work on even when you know what you are doing. Stick with doing normal preventative maintenance to you system and leave the repairs to the pros.

I can not give any information without a complete visual and hands on check of your system and SAFETY devices. If anyone gives you things to check and do, do it with great caution.

This is more then a do it yourself operation.

Lastly, at 17 years old, you are quickly approaching the 20 year life expectancy. Not that it can’t last longer, but must be properly maintained and inspected be a qualified technician annually.

Now with the legal stuff behind us, let’s look at you system keeping in mind what I said.

First, I think you know the 190-200 is the maximum temperature range the water will get. Your setting is normal as long as it’s accurate.

Next, it makes no difference if the relief is horizontal or vertical. It will relieve you pressure. It works on the pressure at it's inlet against a spring. Pressure pushes againt the spring opening the valve.

What you are telling me is that your unit started to cycle then quickly re-starting is telling me that one or more SAFETYS are not closed.

You said it started working after you removed the PRESSURE relief. Well that may have been your problem. Your system may have had too much pressure. Normally you should see between 5 and 10 psig. Pounds per Square Inch Gauge. You may have a bad pressure limit switch or it is not accurate.

What can cause this to go up? Bad automatic make up valve. Manually over filling the system or, now the biggie, bad expansion tank. The expansion tank has a bladder of air inside. As the water heats up, it expands. This expansion is absorbed by the expansion tank's bladder. If the tank is bad, the water has no place to expand to and the pressure in the system goes up and causes the RELIEF valve to relieve pressure and trip the pressure safety switch. If not properly set to around 10 psig on most system, it then fails the system and the unit won’t heat the water.

I think now you see why this can be dangerous. If you don’t know what you’re doing, you can damage the boiler at the bottom end to blow up the boiler at the top end.

Take care and be careful. I know this was long but I want you and anyone else that may read this to be SAFE.