I put a sealant in my CH system about a month ago and it worked well - the pressure stopped dropping in the boiler. However, since the cold weather the pressure has started dropping again. I am presuming that the leak has returned. I will probably need to get the leak fixed properly but in the meantime is it okay to put more sealant in? I can't find any guidelines about how much or how often to add sealant to a CH system. I have a combi condensing boiler. Thanks.