Category Archives: Plumbing

Plumbing Update

Water Switch On.

I finally switched on the water supply to the house and then checked the compression connections on the gravity based system for leaks. The reason for using the gravity based system was to keep everything as simple as possible,  consume the lowest amount of energy and have a system that would be low in maintenance cost.  All the joint connections were brass compression fittings and I used a pipe called  “qual-pex” .  I insulated the cold and  hot water pipes for both the rainwater and the calorifier tank.

Gravity Tank 

I installed a  separate gravity tank for the toilets that will be fed from the rainwater tank in the garden eventually. I need to design a control unit to pump rainwater when required and operate from the mains to flush out the gravity tank at regular intervals. At the moment it is connected to the fresh water supply for testing.  This tank was mounted 2.71 metres above floor level.  Nylon washers were placed inside and outside of the tank brass connections fittings.

Storage Tank Connections

 

 

 

 

 

 

 

What worked for me in relation to the toilets was an 1/2 inch pipe that ran a distance of 15 metres approximately with a storage tank base to floor height of 2.71 meters and this enabled the cistern to fill in approximately 1 minute 45 seconds.

Lessons Learned

  • When tightening compression fittings- a good bit of advice is always leave room for an extra turn on the thread. In this way if there is a leak one can tighten the compression joint further.
  • On the calorifier connections use Jet Blue Plus paste or similar paste and check it is suitable for potable water.
  • The longest run was approximately 20 meters of 1/2 qual-pex and this  supplies enough pressure for a “natural” water flow at the furthest away sink outlet-I also removed the filter in the outlet of the tap to further increase the water flow.
  • Certain isolation On-Off valves have bore diameters that are smaller than the diameter of the pipe bore further reducing the capacity of the water flow. Visually check before purchase.
  • Check that the taps and shower fittings are designed for a gravity system. I used a tap that had a minimum operating pressure of 0.1 bar from the Grohe range (1 metre height of water is = 0.1 bar).
  • I was unaware of what an air lock can look like . In one case no water flowed and in another case I had a constant trickle of water with no air gurgling. To get rid of the air lock I used a small 5 litre pressure sprayer with a silicone hose on the end.Pressure Sprayer

 

 

 

  • Use copper inserts instead of nylon on “qual-pex” when trying to get gravity to work in your favour . They have a wider bore (see below).
Qual-Pex Inserts Copper and Plastic
Copper versus Plastic Inserts

 

 

 

 

 

 

 

 

Toilet Cistern

As most of the inlet valves on toilet cisterns are now designed for high pressure they come with a restriction devices and sometimes a filter. For use on the gravity system I removed these.

I plan to filter the water at the feed end of the water supply.  Both the toilet storage tank and the calorifier storage tank (supply’s the hot water) are within the thermal envelope. This means that the tanks will not freeze but this brings other issues to be dealt with, such as noise from filling and potential condensation. I installed rockwool insulation around the tank to minimise temperature differences of the indoor air and reduce the noise of water filling the tank as I have no attic space.

The original toilet had a bottom inlet valve made with plastic threads which proved difficult to install.

Cistern Inlet Valve

 

I did have problems with the original cistern valve where I cross threaded the plastic connection (which resulted in a leak) as one finds that space is limited under a toilet/cistern (see below).

Toilet Cistern with Penny valve for turning water off and on at the toilet.
Toilet Cistern Connection

 

 

 

 

 

 

 

 

Another problem I had was I could not get it to operate correctly from the gravity tank. To solve the above I replaced the inlet valve with a Jollyfill telescopic Wirquin brass inlet valve and removed the high pressure device.

Wirquin Bottom Inlet Valve

 

 

 

 

 

 

 

 

When I installed  the inlet valve the connection leaked between the rubber seal and cistern. I removed it and placed silicone above the rubber seal. The silicone cured the problem.

Shower

The gravity flow rate proved too low for the shower valve temperature control to work so plan B was acted on. I installed a 1.5 Bar 250w pump to raise the flow rate.

It is a Salamander RP50PT pump (45.5 dBA) . It cost €200 including postage. I am impressed with the low non-intrusive noise it generates. It comes with small sound isolating pads. One can roughly equate a 3dBA increase with twice the loudness.

Another factor to take into account when selecting  and sizing a pump for one, two or three shower units is that the power usage approximately doubles when one selects a 0.5 bar increase for this range of pumps.  So If one is sizing for the use of 3 showers being on at the same time (using one 3 bar pump) and only one  shower is on then one will be using 1000 watts of power most of the time . I feel it is more energy efficient to install separate pumps and in this way one uses the least amount of energy most of the time and the pump will also be quieter as noise increases also with each 0.5 bar of pressure.

Shower Pump
Salamander

 

Hot Water Tank

Mains Water Plumbing

The hot water tank is a 300 litre stainless steel tank. Stainless steel is better at reducing stratification (minimising mixing) because it conducts less heat compared to copper. Different grades of stainless steel exist for different types of water (hard/soft). One also needs to check the type of welds used on the tank as some can not cope with certain water types.

The tank was modified to allow me to connect the solar PV water heating system (previous blog) in the future using thermosyphonic action i.e. hot water is lighter than cold water so it naturally flows from the top of the tank to the bottom (Reducing the need for pumps). The DC power from the solar panels will be connected to electric heating elements. As the solar power varies the heating elements will adjust the output power through a control unit I am developing.

Self Build Design
Self Build Design

IfI install a solar hot water system or another method in the future this will be done with a plate heat exchanger rather than a coil. I installed extra connections on the tank for this reason. The reason for the heat exchanger is that the tank will heat from the top down. A plate heat exchanger looks like the following

plate-heat-exchanger
Plate Heat Exchanger

 

 

 

 

 

 

 

 

 

 

If one opts for a coil it creates turbulence while heating the tank.  I found it difficult to find a tank manufacturer who will install the correct surface area of a coil for a climate like Ireland. I feel most are designed for hot countries like Spain where the sun shines and stays shining. If one opts for a coil rather than a plate heat exchanger one requires a large coil surface area to ensure that most of the solar energy transferred in the least amount of time and the temperature returned to the hot water solar panel is at a minimum. In this way the hot water solar panel can operate at its maximum efficiency.

 

Plumbing Design

Mains Water Plumbing

Initially when researching the options available to plumb the house I came across two  main methods- Pressurised/Closed or Gravity/Open. I settled for a gravity based system because of the simplicity, DIY, reduced parts and maintainability. If one can increase the height of the gravity tank the pressure will increase at the taps.

Below is a video of what a pressurised/closed system can do (if it goes wrong and probably very rarely). When I was researching pressurised systems I felt that there seemed to be different ways of designing these and providing the necessary safety levels. I do not like systems where there are potentially hidden failures (when a safety device is supposed to work and does not).

Showers

I also was hoping to use gravity to supply the showers but it is becoming more difficult to find a good choice of shower valves and shower heads that work on low pressure .  The way around this to keep things simple is to install a shower pump in a central location for two of the showers (see below). One can then use a shower head that helps control the flow rate and keep the water use to a minimum.

For one of the showers I already have a shower valve and head that works well on gravity so I will plumb this separately directly from the tank (shower 3 in the layout below).

Design

The plumbing layout for the house is shown below. (The toilets are fed from a separate gravity tank supplied by the rainwater harvesting system as shown on a previous blog.)

Plumbing
Gravity Fed Design

Materials

I am using Qual-Pex for the plumbing in the house. It varies in price so it is a good idea to shop around (The 1/2 inch varies from €70 to €200 for the same pipe). I ended up using 200 metres  of 1/2 inch and nearly 50 metres of 3/4 inch and 25 meters of the 1 inch.

The overflow from the tank needs to be well secured or finished in copper to ensure that if the tank overheats the pipe will not sag/bend or cause a restriction.

The brass fittings are cheaper than the quick connect so I will use these. One needs a good plastic pipe cutter as using a hacksaw is not feasible. I used a Ridgid brand plastic pipe cutter and I am very happy with the quality.

With a plumbing design one needs to ensure that the size of pipes are no bigger than they need to be. One reason for this is that the volume of water in the pipe will cool down and one has to wait for this to run through fully before getting hot water at the correct temperature.

I calculated that  10 meters of 1/2 inch pipe holds approximately 1 litre of water and 10 meters of 3/4 inch holds 2.3 litres. This gives one an idea if a solution is required and the wait time.

The cold water pipes will be insulated as I am concerned that condensation could occur on the surface of the pipe.

I also tried to ensure that the number of connections/joints are kept to a minimum and I tried to place these only at accessible points.

Logistics of getting hot Water to the furthest points.

The kitchen sink hot water supply is too far from the tank so I may develop an on demand system that ensures hot water is available once certain taps are used rather flushing semi warm water down the drain and a one or two minute wait for hot water. Installing instantaneous heaters is not economical.

This on demand system is used in the USA for closed systems and two companies have developed a solution. One is http://www.gothotwater.com/on-demand-water-heater and http://www.taco-hvac.com/media/09.16.14_HotLinkCutSheet_100-93.pdf. The first solution costs around $660 -too expensive.

A way to solve this is only use one 12 volt pump and have a valve at each sink position. This pump will then feed into the gravity header tank rather than the hot water tank (I need to check the regulations) . I want to keep the plumbing connections and electrical devices to a minimum. The power to operate this can be a small solar panel charging a battery.

The plan is to develop a solution around the following -Measure the hot pipe feed temperature, Detect if the tap is going to be used and link this to controlling the pump and valve.

The only item that needs to be purchased is a 12 volt pump and a 12 volt valve and develop the control unit to suit the Irish regulations. I have started on the design of this. In the meantime I will install a third pipe in the bathroom and kitchen for the final solution.

 

 

 

Rainwater

Rainwater System

As discussed in an earlier blog I will use the rainwater system to feed the toilets and one outside tap. I have started to install the pipework internally . This involves running a 1/2 inch pipe to each toilet.  I note that the Drainage and Waste Water Disposal building regulations state that the pipe used must meet the following-“ for rainwater green / black / green bands and the words RAINWATER in black lettering“.  I rang around and no one appears to stock this in Ireland. I note it is available in the UK. Instead I have marked the pipe with permanent marker in the above colours with the words RAINWATER. An image is shown below.

DIY Rainwater
DIY Rainwater

 

The planned schematic of the rainwater system is shown below.

Rainwater Harvesting
Rainwater Harvesting

I note that some rainwater systems top up the main tank in the ground if one runs short of water in the summer. I have opted for the header tank where I can manually top  up this smaller tank with fresh water or let it automatically bring fresh water to the tank for the duration of the drought with the control unit I built. I feel that topping up the main tank with fresh water is more wasteful.