Plate heat exchanger for DHW on wall hung boiler?

Brad White

are set up for quick response, some storage will go a long way toward stable operation. Even a 20 gallon low-boy.

The Viessmann Vitodens combi unit has such a PHE setup, good for the so-called in-law apartment and fast response. If you do set up such an arrangement, it may cost you as much as getting a package. Other manufacturers may offer something similar. Monitor MZ has a model that does make DHW via a "flash" internal exchanger, but it does not modulate for the heating side; it is on-off.

The other part is, some plumbing codes want double-wall vented exchangers to prevent cross contamination between boiler and potable water should the plates leak. Make sure yours complies.

I would put in at least a small indirect and set it up DWH priority.

Also, if a boiler is to be small enough to heat the apartment, (say a 50 MBH input model such as the Lochinvar Knight or Munchkin) it may fall short on DHW production in an "instantaneous mode", without some storage to draw upon during generation.

My $0.02

Brad

jareedo_2

Plate heat exchanger for DHW from wall hung boiler?

Has anyone tried using a plate heat exchanger w/ tempering valve on a wall hung gas boiler for DHW? I have a small apartment that the owner wants to isolate from the rest of the building w/ seperate boiler ,water heater etc.I definately am going to put a wall hung boiler but instead of using an inderect water heater I'm thinking of using the combination mentioned above. What do you think?

Home Depot Employee_2

T/T

Take a look at the Triangle Tube Mini-Smart, it was designed for just this purpose. Used it once for radiant in a woodshop with a PS110 and supplied DHW to a shower, bathroom and 2 slop sinks.

[Deleted User]

been there

i have used flat plates in the past to produce hot water in a few apartment which boilers coils wheer shot and because of the way they where piped we where unable to replace so my buddy and i hookes up a flat plate through a zone valve and set it up as proirity and with a thermostatic valve ,there was a lag on the inital production which the tenants wheer used to but they whrer able to run all faucets and the shower some thing they had never been able to do it worked out excellent every one was happy .i would say that even with the small lag time it worked out better then we had though and produced more then enough hot water ,this was hooked up to a well water system which had very cold water we used a small 3/4 sweps plate exchanger i believe it was in the 75,000 btu rating we where getting about a 75 to 85 degree temp rise across the plate and it was producing like 3.5 to 4 gpm not bad for a 125 bucks peace and good luck clammy

Vernon P. James_2

look at

Look at NY thermal TI boiler. Deep modulation which will allow over sizing the heating but enough to do the domestic. The 200 will do about 5 gpm for domestic but will modulate on heating from about 30,000 to 200,000 btu's

Aidan (UK)

Combination boilers

Viessmann model WB2 6-24C.

Most boilers installed here are wall-hung condensing combination boilers. The plate heat exchangers are liable to scale up in areas with a hard water supply and their narrow waterways are liable to get blocked with sludge in the existing heating system if there has been a problem with corrosion.

Tony_23

Baxi

Built in plate water heater with priority and 3.5 GPM production. Problem is firing rate on lowest modulation for space heating is 35K. It does have a 3 minute delay to prevent short-cycling in heating mode.