Closed Crawl, Radon, DHW Replacement, Sump, etc…..
I recently bought a house that is in general working order but needs some upgrades.
First, the problems:
– The current 30 gal DHW tank is probably on its last legs. It is located in the vented crawlspace and is not installed properly; it is sunk in the ground ~2 ft and has incomplete retainment surrounding it (see picture). This is the low point in the crawl and there is no sump pump currently installed.
– The house failed the radon test by a slim margin and will need mitigation.
– The furnace is in the crawlspace and does not have ducted combustion air.
This is the work I am considering:
– Ideally I would like to replace the DHW tank with a closed combustion tankless unit. The cost may be prohibitive if the main gas line is too small, so I may need to go with a closed-combustion storage tank unit. The benefit of going tankless would be that I could use the existing hole that the tank sits in now as a sump. Additionally, bc it’s in the crawl, installing a bigger tank may be difficult if possible at all.
– Install a sump pit/pump or leak sensors w/ shutoff valve on main.
– Provide high/low ducted combustion air to the furnace. Replacement w/ closed combustion furnace at this time is not in the budget and the unit, while 18 years old, is in fine working order.
– Install a passive radon mitigation system w/ perforated pipe per EPA specs. Vent using the current DHW exhaust chase but re-line with PVC. This assumes the closed combustion DHW can be exhausted through the wall, but I am not certain if that would work or is allowed. I plan to monitor the radon in the house and the system could be toggled to an active mitigation system by depressurizing under the poly via an exhaust fan installed in the attic.
– Seal-up the vents and carry the poly liner needed for the radon mitigation up the wall to first row of brick (see picture), then insulate the walls with 2″ of XPS or fire-rated polyiso so my floors can be warm and my water lines and mechanical equipment will no longer be ‘outside’.
The DHW needs to be replaced, but I feel like I need to do everything at once. I’m posting here to see what everyone’s thoughts are on my proposed solutions. Also, I’m planning on doing much of the work myself, so if anyone spots any significant code issues/red-flags please let me know. The house is in Denver which uses the 2006 I codes. Looking forward to your response! Thanks.
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