I have a home built in 1965 +/- two years. Under the kitchen sink there is a TP valve installed which vents outside the house when triggered. It has now begun to leak on a regular basis until I release the valve and the sediment or whatever is causing the leak passes though. This is happening enough that I feel I should replace it. My question is, can it just be capped? I've not been able to find any reference to installing a TP valve anywhere except on a hot water heater. There is no instant hot water installed under the sink so I have no idea why it was ever put there in the first place.