@mjr If Vaillant didn't have these parts in Germany I would agree. But they are apparently widely available across the EU, with distributors often offering 1-2 day delivery.
@phowardstutterheim Most components inside the units are from other manufacturers other than valiant. As long as they are similar and an alterative product, there will be no problem with performance.
Professional heat pump installer: Technical Director Ultimate Renewables Director at Heacol Ltd
My husband regularly flushes the external components of our GSH system (heat exchanger, pump) as clay particles enter these and foul them - he also uses acid in this process.
Sorry... I don't follow this statement.
If your husband is flushing through a sealed/pressurised circuit which includes the heat exchanger and pump, then how is that body of water being re-filled after the process?
What chemical inhibitors are being added during the refill operation? None?
We have an open loop system that involves a borehole pump, a buffer tank, a pipe run to a plant room, a variable speed pump, and a plate heat exchanger - all that come before the Vaillant heat pump. Very fine clay particles are suspended in the borehole water - some settle in the buffer tank, but some enter the pipework and end up in the variable speed pump and the plate heat exchanger. These must be regularly flushed out as clogging prevents flow, which stops the heat pump from functioning. The heat exchanger copes with backflushing quite well, but the pump can erode due to abrasion after a few years and has to be replaced. Hope this answers your question..
That's excellent information @phowardstutterheim and having a system diagram is immensely useful to us 👍
I don't know what pump you have on the open loop section, but are you aware that there are models specifically designed for this situation? They can have brass or stainless steel bodies, rather than cast iron.
You can also have filters which prevent clay particles passing through to the plate heat-exchanger. I use one of these on the DHW feed from my well. But you can have several in parallel in order to avoid restricting the flow-rate and allow for ease of maintenance.
You should have received instructions on running and maintaining this installation from your installer.
It's stipulated in Part L Section-7 of the Building Regulations.
Do you have a letter from your Local Planning Authority (LPA) which confirms that they received the Building Regs paperwork within 30-days of installation?
We have an open loop system that involves a borehole pump, a buffer tank, a pipe run to a plant room, a variable speed pump, and a plate heat exchanger - all that come before the Vaillant heat pump. Very fine clay particles are suspended in the borehole water - some settle in the buffer tank, but some enter the pipework and end up in the variable speed pump and the plate heat exchanger. These must be regularly flushed out as clogging prevents flow, which stops the heat pump from functioning. The heat exchanger copes with backflushing quite well, but the pump can erode due to abrasion after a few years and has to be replaced. Hope this answers your question..
Have you not considered installing a duplex filter before the pump and heat exchanger etc.?
It may then be possible to manually or automatically backflush one filter whilst the other is in service.
We thoroughly investigated filters that might be installed to remove the clay particles from the water before the pump and heat exchanger. Unfortunately, fine clay particles are extremely difficult to remove - they clog up filters very quickly and must be cleaned very frequently - too frequently. Filtration systems have been tested for the UK (made in the USA) but the minimum cost of such a filter is around £20,000 - only feasible for large-scale systems. We were advised on multiple occasions by the GSHA to replace the borehole with a horizontal system, but we would have had to invest another £10K to do this. Regular system flushing and replacement of the pump every 4-5 years allows us to continue to use this borehole water. Eventually, the borehole pump will also give up and have to be replaced, but this is an expense of £300-400 - and, so far, so good.
@transparent We have no idea about Building Control - we didn't know they should have been informed about the GSHP system installation and, as far as I know, they were never notified by anyone involved - drillers, installers, etc.
We received handover documents from the installer but there was no mention of anything to do with water quality or corrosion inside the GHSP.
Is there some action that you advise that we should take now?
At the time the system was installed, in 2015, no one (GSH system designer/engineer, installer, even the specialist hydrogeological/hydrothermal company we called in to advise us when the first borehole that we drilled failed due to improper lining) said anything about clay particles and their effects on our system. Of course, we carried out the standard borehole water quality checks, but there were no problems noted - these checks were not related with clay particles, but with salts, etc.
We had to have the borehole drilled three times to get a supply due to faults in drilling, not to a lack of groundwater. I learned more about drilling boreholes than I ever wanted to know in the process - one driller had to refund our money, and a second one had to drill twice, as they failed to line the first borehole properly. This is why we called in the hydrogeological/hydrothermal company - for the inspection of the failed boreholes and design of new boreholes - but they also never mentioned clay, even though our property is located in the famous Gault Formation near Folkestone.
After a year or so, we started experiencing problems with water quality. We investigated with every heat exchange supplier/manufacturer in the UK whether there were heat exchangers that could tolerate the clay particles but learned that, for our size of system (17Kw) there are none - these are manufactured only for larger systems. We also investigated pumps with numerous pump suppliers/experts and open loop installers and came up with the Grundfos TP 50-120/2 A F A BQQE 230v, which is what we now have installed.
We have to live with what we have; we have to make this information available to others. We have advised people in our area who are on clay and are thinking about open-loop systems to think again. We understand that the advice across the UK now is not to install open-loop systems in areas with clay substrates.
We also investigated pumps with numerous pump suppliers/experts and open loop installers and came up with the Grundfos TP 50-120/2 A F A BQQE 230v, which is what we now have installed.
I've looked up that model number and it has a cast iron pump body. However there is an equivalent model in stainless steel which has exactly the same flanges. It can be a bolt-in replacement for what you have.
We have no idea about Building Control - we didn't know they should have been informed about the GSHP system installation and, as far as I know, they were never notified by anyone involved - drillers, installers, etc.
That's an important omission. At the very least your installation would need to comply with Part L (Heat & Power), and Part P (Electrical installation). Did you not even receive an electrical safety/test certificate?
Notification to your LPA is required within 30 days. Here's that requirement stipulated in Part L:
A heat-pump also requires permission from the Distribution Network Operator (DNO), which is UK Power Networks in your region. The LCT (Low Carbon Technology) Application Form is available on their website.
The DNO would usually write back to the installer, who would pass a copy of that letter to you.
This is important information for the DNO, especially as your GSHP & borehole pump use single-phase electricity. 1-phase heat-pumps and EV Charge Points take substantial amounts of current which causes phase-imbalance in the transformer at your local substation. The DNO uses these registrations to monitor their network and reduce losses.
Both the Building Control certification and the LCT approval form part of the documentation which is required if you ever decided to sell your house. The purchaser's solicitor will send you Law Society Form TA6, which asks questions about the property. Section 4 concerns alterations for which Building Control certification is required. Section 12 covers electrical/heating works which must be undertaken by a qualified person.
You are expected to submit the documentary evidence alongside the completed TA6 Form.
Your DNO and Building Control Dept (of your LPA) are usually very helpful.
Their main concern is that installations are safe and that only approved hardware and procedures have been used.
Either your original installer, or you as the property owner, can contact them and ask for help in making a retrospective application.
This post was modified 1 year ago 3 times by Transparent
So you should've also received the matching electrical test certificate from the qualified electrician who connected the GSHP to your existing consumer unit.
You are brill! Didn't know I had a Building Control Application for the GSH system! I have the DNO and the electrical test certificate, the HW Commissioning certificate, and the HP commissioning certificate, and the MCS certificate. So it appears that all is legal.
BTW - I've been looking for 'official' guidance on corrosion protection all day long. I can give you a list of installation/guidance documents from various organisations (e.g. MCA, BRISA, GSHPA, but haven't so far found a word on corrosion protection for heat pump systems (I can't access some, as I'm not a member). Vaillant puts out only guidance for boiler / heating systems in general. A few companies offer 'GSH-specific' corrosion protection products, such as Hydratech and Sentinel. I've now asked the GSHPA to look into it for me, based in part on the discussions on this forum. It seems as though it is expected that Heat Pump installers are also trained as plumbers, or are familiar with general heating system installations...
It seems as though it is expected that Heat Pump installers are also trained as plumbers, or are familiar with general heating system installations...
Yes. But they also need to be electricians and registered with one of the organisations which oversees their qualifications, such as NICEIC.
For that reason it's difficult to install heat-pumps if you're a typical one-man business, operating in rural areas. You either need a partnership between an electrician and a heating-engineer (usually Gas-Safe registered) or else part of the job has to be sub-contracted.
That makes it easier for bigger/national companies to tout for work as HP Installers, rather than a local tradesman who relies on having a good reputation.
Perhaps that's why you don't appear to have benefited from 'local knowledge' on the matter of borehole drilling, lining, clay, acidity of ground-water etc. Buying in (expensive) expertise from further afield doesn't compensate for the experience which a local tradesman can offer.
Given the size of your borehole pump, I assume that the hole isn't very deep.
In Southwest England we drill boreholes 200m deep and more. A loop of collector pipe is lowered into that, forming a closed system with glycol in it.
I very much agree with you discussing these issues with others in the area. It will greatly assist with expanding the 'body of knowledge' about energy matters. Ofgem has identified the general lack of public knowledge as a hindrance in our progress towards renewable-energy uptake and technology advancement.
There are far too few MCS-accredited heat-pump installers for the UK to meet the Government target of Nett-Zero (CO2 emissions) by 2050, and the number isn't growing sufficiently. Moreover, MCS continues to weed out the cowboys and remove them from the industry.
As Brendon @heacol mentioned here earlier, the actual component parts are pretty generic and simply 'bought in' by the well known manufacturers whose name is on the outside of the box.
A GSHP has far less complexity that an internal combustion engine, and could be assembled from the basic components relatively easily. People don't do that because
such an installation couldn't attract the Government subsidies
specialist knowledge and care is needed in handling the refrigerant
But those constraints are keeping the costs artificially high, and providing too great an opportunity for cowboy installers to operate, charging excessively.
The situation is now occurring where DIY knowledge has reached the point where retired engineers (for example) can ignore the grants and simply buy the components they want directly from the plethora of companies in the Far East who are ready to supply them.
We are already doing this properly and safely with domestic Electricity Storage Batteries, as can be seen from discussions here on this Forum:
