Hello
I hope someone here can help me with an issue I seem to be having.
Just moved into a new house (5 bedroom/ 3 bathrooms) a few months ago. First thing we decided to do was replace the boiler as it was 20 years old and didnt want to risk anything over the winter months with 2 small children. At the same time, we also decided to replace the host water cylinder with a megaflo.
The problem we seem to be having is that we run out of hot water at night after my wife has given the kids and herself a shower. It seems to last approx 20 mins or so (and she usually turns off the shower to conserve water when soaping down the kids). I ran the shower one night as well and timed it to see how long it ran out of hot water and it was 20 mins continuous running. I normally take a shower in the morning and never run out of hot water although I am probably in there for 10 mins or so.
Now down to the technical bits.
The Boiler and Megaflo were plumbed in to the existing pipework (i.e. we did not run new pipe throughout the house). The old Cylinder was upstairs in the airing cupboard and the old Boiler was downstairs in the utility room next to the Garage. The new Boiler (Vaillant Ecotec Plus 637) was placed directly above where the old boiler was and the new Megaflo (Indirect
300L) was placed in a corner of the Garage. Length of 22mm pipework from boiler to megaflow for the flow is about 3 lengths of 22mm and the same for the return.Please bear with me on this....
The flow from the boiler went into a 3 port zone valve. One side is for the CH and the other for the HW. The HW flow also has a 2 port zone valve (as required by Megaflo). I had vaillant come out to check the boiler and he confirmed that the boiler was OK. He remarked that he had never seen an installation with a 3 port valve. The installer confirmed that a 3 port valve is a valid combination, but agreed to change it to a 2 port valve to see if that will help clear the problem. Well, it didnt. The following week, Heatrae Sadia came out to check the Megaflo. He remarked that the flow and return of the pipe into the tank were joined with a bypass valve and this is not required;. In addition, the bypass valve was rated between 0.1 and 0.5 bar. As the sealed system is always running near 2 bar, the water would take the shortest route and most of it would go through the bypass valve and not into the tank. I contacted the Installer again and they came around and removed the bypass valve. In all fairness, he realised his mistake and said it should have been one between 1 and 5 bar. He had put this in as an additional safety measure, although one is not required as the boiler has one built in.. Now I thought this was going to cure my problems, but it didnt. I still run out of hot water after 20 mins. I have looked at the Megaflo installation book and the pipework seems to match whats in the book, so as far as I can tell, it seems OK.
Other points worth noting:
Pressure is very good - Dont have an issue with it. When the hot water runs out, the pipe at the top of the megaflo is cold. Other taps only produce cold water. I checked this to see if it was the thermostatic valve in the shower. Shower that is used most often and when the water runs out (not tested with the other one) is one of the old Aqualisa with a grey thermostaic cartridge (dont know what the flow rate is on these). Vaillant checked the 2 port valve and when he turned off and on, he could "feel" the water flowing (plus the slider on the valve moved). HW & CH is on constant on the timer. I let the thermostat control the CH and I want to have the HW heated and ready to go into action (not that it is capable of doing that at the moment). CH works like a treat. House is about 3500 sq ft. Other quotes I had when trying to choose an installer were suggesting a 100k BTU boiler due to the number of Rads I have (19 in total mixture of Towel racks and single/double/small radiators) I ended up going with a 126K BTU boiler. Installer is giving up as they cant find anything wrong. Was not impressed with the Heatrae Sadia Engineer that came out. He put a meter on the tank to see if he was getting a signal and that was it. Didnt do much else. Wife is giving me an ear bashing as the Megaflo was my idea.
Would appreciate any help anyone can give in trying to help resolve this problem.
Many Thanks in advance.
Bernard