Basement heat with HTP Crossover

markwl

I have a HTP Crossover Floor model for domestic hot water
https://www.htproducts.com/RGH75100.html

Does anyone have experience with these units for heating?

They have a heating kit to connect this to an air handler. I'd like to use this to heat a 500 sq ft basement, open plan, r10 insulation on walls, in SE Michigan. The basement heats up fine with two 1500 watt plug-in electric radiator style heaters.

Wondering if I could connect it to something like this
https://www.supplyhouse.com/Beacon-Morris-K84-K84-Twin-Flo-III-Kick-Space-Heater

Thanks for any ideas/advice.

Ironman

You don't wanna directly connect the water heater to space heating as legionella and other nasties will breed in it. Use a heat exchanger between the water heater and whatever space heating appliance you choose.

As far as the toe kick goes: I'd use the 120 model. You'll also need the enclosure for it unless it's actually going in a toe kick. Also, the low temp aquastat for it.

markwl

Thanks for the quick response, much appreciated. Any recommendations on a specific heat exchanger?

Ironman

Just a sufficiently sized plate HX, probably at least 5x12x30 plates. You'll need a stainless circulator on the domestic side and a standard circulator and relief valve on the other side. Also a means to fill and purge on the space heating side.

Taco makes an all in one device call the Xblock. A little pricey but has everything in one unit.

mattmia2

I'd suggest a panel radiator or fintube baseboard instead of a kickspace heater. The panel radiator can work more effectively with lower supply water temps. Supplyhouse I don't think carries more standard european panel radiators which will be less expensive than the runtal radiators supplyhouse carries.

How will you use the space? will you heat it all the time or will you turn the heat on when you go down there? If the latter, I would oversize it so that you can warm the space quickly.

markwl

Thanks for the suggestion, it would be heated all the time. The manual for the HTP indicates connecting to an air handler for heating - would this have any advantages vs. a radiator?

hot_rod

Those combi systems are often done with air handlers. The coil in those air handlers do not hold much water. So the ability to flush them with a daily run cycle is fairly doable.
If you do a combined system everything needs to be non ferrous and it should also be all low lead components. NSF 61 is yet another step up for low lead piece of mind.

markwl

Right - so in that case would going with an air handler mean I wouldn't need the separate heat exchanger?

My thought with the toe kick heater referenced above was treating that as a sort of mini air handler, it would be installed basically right beside the water heater resulting in a very short hydronic run.

hot_rod

markwl said:

Right - so in that case would going with an air handler mean I wouldn't need the separate heat exchanger?

My thought with the toe kick heater referenced above was treating that as a sort of mini air handler, it would be installed basically right beside the water heater resulting in a very short hydronic run.

I guess you need to balance the risk factor against the convenience of building a combined system.
I'd say most every building or home has "dead end' legs in the hot water piping where water can stagnate. Hotels, vacation homes, seasonal resorts all are subjected to this condition. I have a couple outdoor showers that will not see flow for months in the piping. I'll run them for a few 5 minute before inhaling the vapor. I'm on a well and do not have any chemicals added to deal with potential bacteria anyways.

With a short run, low water capacity and the ability to flush it occasionally you may be in better shape than most buildings.

It's really a judgment call on your part, as combined systems are still legal and manufacturers sell and promote them.

Actually it is one of the most efficient way to get the heat energy from the heater to the occupant, eliminates additional HX, piping, pumps, controls.

mattmia2

You could run the water heater above 140 and temper the output.

Quite possibly the simplest and most cost effective solution would be to just install a gas direct vent console heater or wall furnace.

markwl

Thanks again to both for the detailed responses. I'll look in to the wall furnace, hadn't really seen those before.

Also probably should have mentioned there's a mixing valve on the water heater, tank is set to 150 degrees and mixed down to 125 for the DHW.

mattmia2

Whatever the fancoil is probably should be made of low lead materials(and any pumps, fittings, valves etc.). Typically hydronic components are not low lead. If you read the code section about low lead components it says something about water intended for human consumption. You could argue that hot water is not going to be drinking water.

hot_rod

I know some folks put hydronic towel bars on DHW recirc loops, so it would ,or should have the low lead listing to be considered safe.
Looks like Myson has their kickspace heaters NSF listed for potable water.

markwl

Okay thanks again everyone, so after more research wondering about a system that uses Runtal radiators. Would use a heat exchanger with the water heater so the heating system would be closed:

https://www.pexuniverse.com/3x8-30-plate-brazed-heat-exchanger-3-4-mnpt

Thinking of stainless manifold with "home run" connections to each of the radiators, something like this:
https://www.pexuniverse.com/ssm212-steel-radiant-heat-manifold

Connecting from the manifold to the rads via 1/2" oxygen barrier pex tubing, 3 in the basement to start each about 4000 BTUs with TRVs. Furthest distance would be 20'.

Potentially expanding to upstairs radiators in the future.

Wondering if that should work, and what circulator pumps would be best for this? And/or if I'm missing anything major?

Thanks in advance.

mattmia2

unless you really want the look of the Runtals, which really are an excellent product, european panel radiators will do more or less the same thing for a significantly lower price.

markwl

Looking at the Runtals for performance and aesthetics.

I'm thinking of using the Grundfos Alpha 2 circulator pump to automate the closed part of the system - would the pump on the water heater side need to be matched to this? Or could something more basic be used?

markwl

markwl said:

Looking at the Runtals for performance and aesthetics.

I'm thinking of using the Grundfos Alpha 2 circulator pump to automate the closed part of the system - would the pump on the water heater side need to be matched to this? Or could something more basic be used?

Main thinking is that is if I add 3 rads in the basement and later on add more on main floor I won't have to change the circulator pump as it will self adjust to the new requirements.

Correct me if I'm misunderstanding how the Grundfos Alpha 2 work.