Hi, sorry to bother you all with this but I am really struggling to find a suitable combi-boiler replacement and a knowledgeable heating engineer to discuss options. Ive tried to note as much relevant details below - apologies if its too long or irrelevant. Any help most gratefully received.
Current System
Supply
Current Issues
New Requirements - Assuming a new boiler is required
Current System
- Our house was built new c11 years ago - The existing system has been in place since that time.
- The house is very well insulated and we rarely use the central heating upstairs, heating downstairs generally suffices
- Floor area 210 square meters.
- We have underfloor heating on two floors. Each floor can be independently controlled and I think have separate piping for the upstairs and downstairs system
- We have three bathrooms - showers are primary usage.
- We have very good water pressure
Supply
- We use an LPG tank as gas supply
- We have a 300 litre thermal heat store powered by solar and wood burner back boiler
- The heat store does not have an immersion element.
- The solar pump system is a Geco G422-PO1.
- We have two solar panels on our roof
- We have a wood burning stove with a back boiler, the heated water flows through the Thermal heat store
- We have a combi boiler Coopra Compact 30K (i think its a 30K). We are probably going to replace this.
- I dont believe these are available in the UK anymore - I think this may be a Netherlands based company.
- I understand the combi-boiler is fed with via mains cold water which is first passed through the thermal store, accepting whatever gain via heat exchange process
- This boiler takes the pre-heated water from the heat store and supplies hot water.
- The boiler does not heat the underfloor central heating. I understand this is a mains cold water supply only.
- This is definitely not a 'system' bolier. It is a combi boiler.
Current Issues
- Our combi boiler is beginning to give trouble and occasionally would not fire when the pre-heated water from the store started to cool below hot water requirement - this led to a warm shower steadily cooling in line with dropping temperature in the hot water store.
- This was not a major issue as we could always rely on the residual temperature in the thermal store to give us enough hot water for showers etc if we had previously used the wood burner. A great insurance against power cuts etc.
- More recently there has been a bigger issue, even with the thermal store at 70 degrees, when you turn on the shower it runs cold. This must mean the hot water demand is no longer passing through the thermal store before being delivered at the shower - this goes for all of the hot water taps.
- When we reset the boiler we can usually get it working again but this isn't sustainable.
- I have checked the pipe coming from the thermal store marked 'pre-heated water feed to boiler' and this is a concern - why would the pre-heated water source be cool, when the store is at 70 degrees and there is hot water demand? Could this be blocked - i don't know??
- We have no 'local' heating engineers as we live in a remote part of the West of Scotland
New Requirements - Assuming a new boiler is required
- The boiler should measure the pre-heated water temp' and only fire if the preheated water is below the required hot water feed temp.
- Looking for max efficiency.
- In the event of a power cut we would like to be able to draw hot water with the benefit of it first passing through the thermal store (as we previously could)
- Ideally we would like the pre-heated supply to feed both hot water and underfloor heating, but would accept hot water supply only.
- Confirm the the 'pre-heated water' feed form the thermal store is operating as it should
