Solar water heating - Domestic

[noname]

I live in a bungalow that had a solar water heating system already installed. Has anybody knowledge of how one checks, and refills if necessary. the primary circuit which, I assume, has an antifreeze/water mix? The system has glass tubes on the roof.

 

[kimbo]

The solar fluid is a special mix which you can get in most merchants or online do not use ordinary antifreeze. It depends on what system you have , you will either have a drain back system of which I know nothing about or a pressurised system which you will either have a pumping station with a gauge that tells you the system pressure which should be normally on 1 bar, this system will need a special solar pumping station to pressurise as there are 3/4 inch tappings to fit the pump to. The simple system is where you have a pump and a check valve and somewher you will have a fill point which may be something like a service valve turned off. This system can be recharged with a garden weed sprayer with the nozzle removed and the spray lance can have a 8mm or 10mm compresion fitting attached to it and the other end of it increased to 15mm, you can then use a filling loop to re pressurise it.

 

[ecowarm]

Do you know the last time it was serviced?

 

[noname]

To my knowledge it has never been serviced. It was in the bungalow when I moved in in 2007. It was probably installed around 2004/5 but This is a guess. I believe the installer went out of business.

 

[ecowarm]

just posted in the wrong thread

 

[noname]

To my knowledge it has never been serviced. It was in the bungalow when I moved in in 2007. It was probably installed around 2004/5 but This is a guess. I believe the installer went out of business.

 

[ecowarm]

I would get it serviced properly what area are you in?
Somebody on here may be able to help

 

[gaspastemania]

if its pressurised then surely it would have a pressure dial somewhere and isnt it glyco you use to put in the primary circuit.

 

[Gray0689]

Pressure gage usually on pumping station and yes glycol is the solar transfer liquid

 

[eco_mark]

you will either have a drain back system of which I know nothing about

They usually use the same transfer fluid, and although technically you don't *need* an antifreeze with a drain-back most people play it safe. Only difference really is that when the pump isn't running the fluid isn't in the collector and 'drains back' into a small cylinder or tank.

 

[noname]

Kimbo

Thanks for your reply.
The system seems to have German parts as there are German words on the foam box around the pump. A 15 ml pipe coming up to the loft from the HW tank goes to a graduated sight glass below the Wilo pump. The sight glass seems to have some brown gunge in it. Next comes a tee to an open ended service valve which is threaded both inside and out at the open end. This should probably be capped off but isn't. The valve is in the closed position of course. Then comes a screwdriver slot of what is probably the service valve for the pump. I noticed that this appears to have graduations around it to indicate the degree to which it is open. The slot is at 45 deg. to the vertical.
Above the pump are the following:- 1) A tee to a stub tube of about 7 ml diameter. Can't guess what purpose this serves. 2) A pressure gauge reading a little below one bar when the pump is NOT running. 3) A 15ml pipe to the solar tubes on the roof. There is also a fitting above the pump from which the following appear:- 1) What I guess to be a pressure relief valve as it has a conical plastic knob on top marked 6 bar. 2) A 15 ml open ended pipe which drops into a plastic container. What is this for? Is it part of the pressure relief system? 3) A corrugated flexible tube which terminates in a blue cylinder. Is this to keep the system pressurised? and 4) A service valve which is capped off with a screw cap. The middle of the screw cap seems to have a small round knob with a plastic retainer strap on it. I am not sure if the retainer strap is for the screw cap itself and the small round knob in the middle is just to hold the strap or if the small round knob itself is an entry point to the system through the screw cap.
I hope you may be able to recognise what I have described. As I say, there appear to be two service valves with accessible ends, one open ended before the pump and the other which has a screw cap and which may be part of the pressure system.
Any further information you can give me about the servicing I might need and what I might be able to do myself would be very helpful. If the pressure drops much below one bar when the pump is inoperative does this mean a top up is needed?

 

[ecowarm]

Kimbo

Thanks for your reply.
The system seems to have German parts as there are German words on the foam box around the pump. A 15 ml pipe coming up to the loft from the HW tank goes to a graduated sight glass below the Wilo pump. Flow Gauge

The sight glass seems to have some brown gunge in it. Probably needs flushing and refilling

Next comes a tee to an open ended service valve which is threaded both inside and out at the open end. This should probably be capped off but isn't. Should be capped

The valve is in the closed position of course. Then comes a screwdriver slot of what is probably the service valve for the pump. I noticed that this appears to have graduations around it to indicate the degree to which it is open. The slot is at 45 deg. to the vertical. Flow restrictor Should be set as per collector panel instructions ie 6l per sec.


Above the pump are the following:- 1) A tee to a stub tube of about 7 ml diameter. Can't guess what purpose this serves. 2) A pressure gauge reading a little below one bar when the pump is NOT running. 3) A 15ml pipe to the solar tubes on the roof. There is also a fitting above the pump from which the following appear:- 1) What I guess to be a pressure relief valve as it has a conical plastic knob on top marked 6 bar. Pressure relief valve


2) A 15 ml open ended pipe which drops into a plastic container. What is this for? Is it part of the pressure relief system? If the pressure exceeds 6bar the glycol is saved in the container for re-use

3) A corrugated flexible tube which terminates in a blue cylinder. Is this to keep the system pressurised? Expansion vessel which takes up the pressure as the temperature rises


and 4) A service valve which is capped off with a screw cap. The middle of the screw cap seems to have a small round knob with a plastic retainer strap on it. I am not sure if the retainer strap is for the screw cap itself and the small round knob in the middle is just to hold the strap or if the small round knob itself is an entry point to the system through the screw cap. Connection points for a solar filling pump


I hope you may be able to recognise what I have described. As I say, there appear to be two service valves with accessible ends, one open ended before the pump and the other which has a screw cap and which may be part of the pressure system.
Any further information you can give me about the servicing I might need and what I might be able to do myself would be very helpful. If the pressure drops much below one bar when the pump is inoperative does this mean a top up is needed?

I would recommend getting some one in as a solar system can be dangerous as it operates at very high temperature and high pressure.

A solar filling pump is around £400 a refractometer is over £100 a training course is around £400 or a professional will
service, flush, refill and test the safety valve and vessel pressure for about £200 maybe more if anything other than the glycol needs changing.

 

[noname]

Thank you kimbo for your very helpful reply. I will make enquiries about servicing. However, if the cost is £200 or thereabouts I am beginning to wonder if it is worthwhile as I have no idea what I save financially in running the system. I am able to see for how long the pump is running over any period of time and can therefore calculate the pump running cost over 12 months, but the saving in gas costs for hot water is beyond me. Thanks again anyway.

 

[ecowarm]

Kimbo???

You will get free hot water for a lot of the year 60-70% and the running cost of the pump is minimal, what controller do you have? some can give you a lot of info regarding running time etc

 

[eco_mark]

As ecowarm says, for the small cost of a couple of hundred pounds or less you can get your system up and running and get 'free' hot water! You've already got the system and didn't have to pay for it, so you don't have to worry about pay back periods like the people who are getting them installed from new. Instead you'll be getting between 80%-100% free hot water during summer months and over the course of a year anywhere between 30%-70%. If the system is hooked up to heat your CH too then that can reduce your energy bill for heating too, even in winter. Not to be sniffed at with the recently announced increases in gas prices.
Post what area you are in and maybe someone here can hook you up with a service.

 

[noname]

ECOWARM & eco mark

The controller is a RESOL (Delta Sol BS) which shows the temperature at the collector, bottom of HW tank, top of tank and pump total running time. On the bungalow roof are 20 tubes, each maybe 1800mm in length. One tube, by the way, is a bit damaged at the bottom and the plug that should be at the bottom is missing. I suppose this reduces the effectiveness of the array but I presume by not more than 5% . The system feeds the HW tank only and the tank has two coils, one fed from the solar panel and the other from the central heating / HW gas boiler circuit.
In 2009 the pump ran for 2024 hours. In 2010 it ran for 1893 hours. The pump is on the 43 watt setting and therefore its energy usage is 80-90 kwh per year. The electricity cost is easily calculated but I have no idea how much heat is transferred to the HW system and the gas units thereby saved.
I live in Watford, Herts

 

[eco_mark]

The electricity cost is easily calculated but I have no idea how much heat is transferred to the HW system and the gas units thereby saved.

Obviously that will depend on a number of factors some of which will change on a daily basis. Things like: size of solar array, amount of sunlight you receive, whether you use your hot water during the day, whether your boiler comes on before the solar has had a chance to heat up your water. If you use the most hot water first thing in the morning then the best way to get more out of your solar system is to change your habits.

The most energy used when heating water is the initial raising temperature from cold ... say 10'C to 20' ... so even if your solar is only raising your cylinder temp to 20' or 30' it is saving you money that you would otherwise be spending on gas. So, free sunlight or paid-for gas?
The energy saving trust have published some numbers for savings, but obviously have to state that they are only examples. All the factors I mentioned will affect your actual savings.
http://www.energysavingtrust.org.uk/Generate-your-own-energy/Solar-water-heating

 

[kimbo]

I think you should be able to set the resol controller to give you how many kw,s it has produced in a day and also in one year. I fitted a navitron system with one of their controllers which looks just like a resol and there are numerous settings, regarding the pump on the navitron system you set the pump to maximum and the controller regulates the pumps speed as required.