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					DEC                        design                                                                   MEMO
DEC       Design         Mechanical             Consultants             Ltd.


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ATTENTION:          Dominic Soave                                     FROM:           William. T. Vaughan P.
                                                                                      Eng
COMPANY:            Taina Group of Companies                          PROJECT NAME:   3827 Sunridge Drive
FAX #:              604 685 2533                                      OUR REF. #:     D04-057
DATE:               August 31, 2004                                   NO. OF PAGES:   2
CC:                 Arden Sauer, 604 894 1859

DESCRIPTION:
Dominic,

Attached is our final schematic of the heating system layout that we recommend. We have not
created any plans of the house since up to date Cad files are not readily available and most of
the remedial work is within the boiler room where the contractor has to work out the exact
layout to suit what has already been installed.

We have shown on the schematic any changes that we believe are essential to satisfactory
performance of the system in terms of reliability and economy. We have not carried out
complete heating load calculations but have relied on the numbers provided by Westmark as a
guide to the loads. Where there is any doubt about these numbers we have carried out
verification calculations.

As you know, the total connected heating loads exceed the capacity of the boilers by a
considerable amount. However since the loads are not coincident, we are confident that there
is sufficient boiler capacity. There is an added safety factor in heat exchange capacity of
components that can be increased by control strategies and changes to water temperature.

We have carried out pressure drop calculations to determine pump sizing using information
from equipment suppliers. The Installed pumps are mismatched to the system and generally
need to be replaced.

The following is an outline of the changes that we have proposed:

       1. The boiler supply and return headers have to be rebuilt to ensure that each boiler is
          fully utilized and all the loads have the same water temperature supplied at any one
          time. The headers also need to be increased in size to handle the water flow with
          acceptable pressure drop.
       2. The present design relies on the pumps for connected loads to circulate the water
          through the boilers. This does not work since at times there is inadequate flow for
          reliable operation of the boilers. We have shown a primary/secondary pumping system
          whereby each boiler has its own pump (primary) that runs when the boiler is firing and

                                                      Westminster Building
Suite 309 - 713 Columbia Street, New Westminster, B.C. V3M 1B2 Phone: (604) 525-3341 Fax: (604) 525-3147
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        each load has its own pump (secondary). This arrangement allows different water flows
        through the boilers and the loads without hydraulic interference.
    3. The current control mixing valve and pump for the radiant heating system are
        undersized, especially when the basement and south side of the ground floor are
        added. Rather than adding a second pump and mixing valve we have replaced them
        with larger units. Because of the importance of the in-floor heating system we have
        shown duplex pumps that provide standby in case one pump fails. We consider that the
        single pump is a weak link in the system that has multiple boilers such that if one boiler
        fails there are others to take over. If the single heating pump fails there is no heat in the
        house.
    4. The snow melting heat exchanger is undersized for the area being served. However we
        have not proposed changing to a larger unit since greater capacity can be achieved by
        increasing the water temperature, although not to the design capacity required. The
        existing pumps are undersized and cannot handle the pressure drop in the heat
        exchanger and piping so we have proposed replacing them with larger pumps. We
        have sized the pump such that if it is decided later that the patio and driveway snow
        melting heat exchanger is too small, it can be replaced without changing the pump.
    5. The decks represent a small portion of the snow melting system so we have added a
        separate small heat exchanger to relieve some of the load from the main heat
        exchanger. If a second sensor is added in the future, this could control the decks only.
    6. There is no modulating control for the snow melting water temperature such that there
        is a chance of shocking the concrete with very high temperature swings. We have
        added a control valve that stops rapid temperature swings and increases the life of the
        equipment and heated slabs.
    7. The expansion tanks for the main heating are undersized. We have not yet sized the
        expansion tanks but will do so shortly. Similarly we will size an expansion tank for the
        snow melting system.
    8. The Pool ventilation system has a heating coil that has not been piped to the heating
        system yet. We have shown a new pump, 3-way control valve and connection to the
        headers for this coil. The controls for the heating coil have to be integrated with the in
        floor radiant system so the two systems do not fight each other. We will be proposing
        the controls for this later.
    9. Several of the pumps do not have check valves so we have shown them added to avoid
        possible backflow from one pump to another.
    10. The main heating system and the snow melting system are served by one back flow
        preventer but there are no check valves to stop cross contamination between these two
        systems. We have added check valves to each make-up.
    11. The gas piping to the boilers does not have proper dirt pockets as required by the Gas
        Code. The piping needs to be reinstalled to each boiler to meet code.
    12. The control system for the heating system is totally inadequate. There many competing
        demands for hot water and it is necessary to have a control system to prioritize the
        loads, respond well to changing loads and operate the systems as economically as
        possible. We are currently working with Teckmar Controls to put together an integrated
        system that will respond to the various loads and outdoor conditions and only run the
        boilers that are needed to meet the load. The existing wiring from room thermostats is
        run back to the boiler room as is the wiring from the control valves, so the provision of a
        central control is fairly easy. The rest of the modifications can be done regardless of
        what control system is installed so we will be submitting a proposed system shortly.
    13. The existing boiler venting system does not appear to be working very well. The
        combustion air duct terminates in the basement, which may be under a negative
        pressure that does not allow proper venting. The duct must be extended to the outside
        wall with adequate free area of opening. We will confirm the size of opening required.
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    14. When only one boiler is running, it may not be able to develop sufficient draft in the
        large B-Vent so we propose to have a minimum of two boilers running at any one time.
        This will be a function of the control system.
    15. The domestic water storage tank may not be large enough for the two massage
        showers and the rest of the domestic water load. Also the restricted capacity of the
        boilers relative to the connected loads may require priority to be applied to other loads,
        the addition of a storage connected to the existing one by a circulating pump provides
        more storage for when the priority is other loads. We have not shown an extra tank
        since it could be added at any time if the need arises.
    16.

Regards,



Bill Vaughan

				
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