Common questions

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What outputs can the different charging units handle?

Laddomat 11-30 - 60 kW
Laddomat 11-30 "Duo" - 40 kW
Laddomat 11-100 - 200 kW
Laddomat 21-60 - 80 kW
Laddomat 21-100 - 120 kW
Laddomat MR 40 - 45 kW
Laddomat M120 – 120 kW
Laddomatic – 240 kW
Laddomat 125 DN25 / DN32 – 60 / 95 kW
Laddomatic 125 DN25 / DN32 – 70 / 170 kW

How can I calculate the output my boiler uses to charge the tank?

The output (in kW) is calculated using the formula: Temperature difference (°C) between inlet and outlet of the boiler (= the thermometers on Laddomat 21) x Flow* (l/h) x 1.16 / 1000

As a reference it can be said that in a “good” system - with recommended pipe dimension and short distance between boiler and tank – there is a flow in Laddomat 21-60 of approx 2500 l/h.

Example:

The temperature difference between out- and inlet in the boiler on Laddomat 21-60 is 10 °C. The output is approximately 10 x 2500 x 1.16 / 1000 = 29 kW.

NOTE! The temperature difference must be stable for approx 10 minutes in order to be able to depend on the calculation.

The boiler’s output can also be calculated by reading off the tank temperatures:

The total energy in the tank is calculated by taking the total temperature increase, for example from 40 °C to 90 °C = 50 °C, and multiplying it by the heated volume, for example 1000 litres.

Example:

50 x 1000 x 1.16 / 1000 = 58 kW

If it took 2 hours to charge the tank full, there is an average output of 58 kW / 2 = 29 kW.

NOTE! One condition is that you know with some certainty how much of the tank has been heated.

What temperature thermostat cartridge should be used with the Laddomat?

Depending on the boiler output, pipe system etc, a higher or lower temperature than the standard thermostat cartridge can be used.

Generally speaking, always select the highest possible opening temperature, to prevent problems with fan stoppage or choking of supply air via the draft regulator.

NOTE! When starting a new installation it may sometimes be necessary to run it at a lower temperature for the first few firings to reduce the problems of air evacuations that occur when heating fresh water.

What is the difference between Laddomat 21 and 10/11 and 4030/MR 40?

Laddomat 21, 21-60 and 21-100 as well as Laddomat 10, 11-30 and 11-100 are used when a hot water heater and a mixing valve are on the tank.

Laddomat MR 40 (former Laddomat 4030) is used when there is a hot water heater and a mixing valve on the boiler. Laddomat MR 40 controls the flow both from the boiler (charging) and back to the boiler (discharging).

What is the difference between CBJ/K, CC and EC Home?

In principle all give a simple control function.

Thermomatic CC and K works with only supply pipe sensor for constant supply pipe temperature.

Thermomatic EC Home uses room sensor and supply pipe sensor as standard, but can also be controled using outdoor sensor and wireless room sensor. See product page for more info.

EC Home: the acatuator can manage max 10 Nm = can manage all normal mixing valves.

CC: the actuator can manage max 13 Nm = can also manage older mixing valves.

CBJ/K: the actuator could manage max 15 Nm.

What size mixing valve can be used?

Too large a mixing valve gives reduced control function. As a simple rule of thumb; a normal detached house with 6 kW max output should be equipped with a DN 15 valve (kvs 1.6 or 2.5). A large house with 12 kW max output should be equipped with a DN 15 valve (kvs 4 or) valve DN 20 (kvs 6.3). This applies to heating systems with a calculated temperature drop of 5 - 10 °C.

Can the sensor cables for your controls be extended?

Yes, unless specified otherwise in the manual, the sensors can be easily extended with two-wire cables, i.e. of the telephone cable type, to virtually any length.

How should a flue thermostat be installed to prevent the bulb from being burnt?

The bulb should be installed on the underside of the flue, where it is a little cooler, with a spacer if necessary. For a complete description and tips, refer to the instructions for the flue thermostat.

What temperature should the flue thermostat be set to?

Exact temperature varies from installation to installation. 50-120 °C is usually about right. It is important that the pump is started soon after firing has started and that the pump is stopped when the fire has gone out. Adjust the value by setting the thermostat to max and lighting the boiler. Then, after achieving a normal firing, turn the thermostat down a little below that temperature, whereupon deployment occurs. Check later when the fire has gone out that the thermostat has not been set too low. If it is too low, the pump runs for an unnecessarily long time, after the fire has gone out.

Why does my Laddomat 21 produce a “knocking” noise?

Laddomat 21 - a "knocking" noise (PDF)
In 9 out of 10 cases it is because there is air in the system or that there is a closed expansion vessel and too low working-pressure.

What is required to service a Laddomat?

The thermostat cartridge

It wears with time, depending on how much it is required to work and how high a temperature it is exposed to. Temperatures close to boiling point cause the thermostat cartridge to wear out faster.

The pump

Usually does not break without a reason. The most common reason is contaminants/air/dirt in the water in the installation accumulating inside the pump, which means that the pump can stop or the bearings wear out, resulting in stoppage/leakage and/or noise. If the pump runs slowly, it may be possible to clean the inside and get it going again. If the bearings are worn out the pump must be replaced. NOTE! A fault of this nature can occur after a very short time and can require special action to rectify it.

Cleaning

When servicing, it is a good idea to clean all sealing surfaces, the non-return valve etc.

The tank is hot all the way down to the bottom, but I want to increase the temperature more. How do I do it?

The best thing is just to fire “one cycle”, that is fired until the tank is hot at the bottom and stop there. The risk is otherwise that the cooling to the boiler will be insufficient in the closing phase and the boiler boils or the fan switches off.

Try changing the thermostat cartridge in the Laddomat to a cartridge that opens at a higher temperature. In this way, the charging temperature is raised for the entire firing, which means that a higher temperature can be obtained in the tank right to the bottom.

Example: You use a 72° cartridge and get 80 °C in the tank. Changing to a 78° cartridge means raising the temperature by 6 °C to 86 °C. It might also be possible to reduce the speed of the pump to achieve a higher boiler temperature. NOTE! "Old" (non ErP) pumps must not be reduced to lowest speed.

How do you make connection when the tank is in the cellar, under the boiler?

Always try to avoid having the tank lower than the boiler. The charging capacity is negatively affected and there is always a large risk of heat retention in the boiler if the tank is placed lower.

If connection has to be made in this way, use Laddomat 11-30/11-100, not Laddomat 21 (due to self-circulation function can't work), and position the Laddomat low next to the tank.

Can Laddomat be used when there is a long distance between the boiler and the tank?

No, for long distances it's recommended to use a Laddomatic solution instead. This is due to the (possibly) high resistance in the Laddomat-tank circuit, which can cause charging to work badly.

Please check the Manual for Your Laddomat for recommended max distance between boiler and tank.

NOTE! It is possible to place the Laddomat next to the tank instead of the boiler, to make Laddomat-tank circuit smaller. It's important to remember though that the hot circuit boiler-Laddomat becomes much larger and self-circulation will be bad or non-existent.

How do I change my old Laddomat to a new Laddomat?

If you for some reason want to change the old Laddomat 21 to a new one, and don't want to modify the plumbing, it's possible to use a Laddomat 21-100 together with an adaptor (our Art. No. 11 20 05) on top.

The iron casting for Laddomat 21-100 has the same width as old Laddomat 21, but it's slightly lower.

NOTE! if You want to use the new ball valves that comes with Laddomat 21-100, the plumbing still has to be modified, as these valves are bigger than the old valves.

I’ve used Product XX earlier. Which product should I use today?

Thermomatic CBJ, ERA 10, ERA 10PE+ and Combi has been replaced by Thermomatic EC Home.

Thermomatic K and ERA K has been replaced by Thermomatic CC, but EC Home can also be used for the same purpose.

If you want to replace an old regulator like Laddomat 3000, SB630, 630.2, K650 or 650.2, then Laddomat MR replaces all of these. The sensors used for Laddomat MR are the same type so it’s not necessary to change them.

If you want to connect extra sensors to read temperatures in the display, it’s possible to connect up to 4 sensors in Laddomat MR.

Also Laddomat 31 or 33P can be replaced by Laddomat MR, but then you also have to replace the sensors.

What kind of sensors do you use for your regulators?

Our most common sensors are of NTC type, 50 kOhm @ 25°C.

You can find a complete Ohm table and for which products and purpose the sensors are used here.

Can I keep my old sensors if I change my old Laddomat 3000/SB630/630.2/K650/650.2 for Laddomat MR?

Yes, the sensors are of the same type for Laddomat MR. You can also complete Laddomat MR with one or two sensors extra to be able to show extra temperatures, as there’s room for up to four sensors.

I’ve had a stroke of lightning and my regulator isn’t working anymore. What can I do?

If the regulator is completely dead, it might be enough to change the fuse/fuses on the circuit board (in case there are fuses).

If the regulator indicates sensor error, it might be a broken sensor, but it might also be some broken component on the circuit board. Check the resistance for the sensors according to Ohm table in the manual or here.

Depending on regulator, it might be possible to repair a broken circuit board, but in other cases it’s possible to order a new part or replacement product.

What’s the difference between TV 4S and TV 4BIV?

The two mixing valves might seem the same on the outside, but they have completely different function.

TV 4S is a 4-way mixing valve, most commonly used on a boiler, to pre-heat the return water from the heating system. The risk of condensation in the boiler is lowered by mixing the colder return water from the heating system with hot water from the boiler.

TV 4BIV is a bivalent mixing valve. This means the mixing valve can for example use hot water from two different sources, or two different levels in a storage tank. If the demand for heat is low, the heat lower in the tank can be used primarily. This is good for layering in the tank as stirring of the water in the top of the tank is minimized. TV 4BIV can also be used as diverting valve, for example to send heat to different levels of a storage tank if solar collectors are used.

To maximize the function of a bivalent mixing valve, the valve should be completed with an automatic regulator, for example Thermomatic EC Home or CC.

I’ve bought a Laddomat with a low energy pump. Why do I seem to get the same flow on all speeds?

On a Laddomat the pump should be set to non-regulated mode. The automatic speed control wont work as the pressure fall on the charging circuit is pretty much the same all the time, which makes the flow constant, no matter what speed setting. In non-regulated mode the pump speed is set manually to desired flow. NOTE too low flow means the boiler might become over heated.

What can happen if I have a too big mixing valve to the heating system?

A too big mixing valve can lead to unstable regulation and bad heat comfort. With an automatic regulator installed, a big mixing valve can make the actuator turn a lot back and forth to get correct supply pipe temperature. The average temperature in the house will probably be correct so it won’t necessarily be noticed on the room temperature in the house though.

If you handle the mixing valve manually, you will notice that it’s very hard to get a correct temperature. Just a small turn on the valve can lead to a huge change in supply pipe temperature, which can lead to huge variance in room temperature and you will have to run back and forth to the mixing valve and change the setting very often.

If I don’t fire up my boiler until the whole storage tank is completely cold, it takes very long time to get the temperature up. If there is just a little bit of hot water left when I start the firing, there is no problem. What’s causing this?

This phenomenon can occur if the mixing valve to the heating system is fully open (because the storage tank and house is cold) when firing begins. What happens is that the flow to the heating system is much greater than the flow from the boiler. This makes the hot water from the boiler getting mixed with cold water from the storage tank. Because of this, the temperature to the heating system will be too low to make the mixing valve start to close. As soon as the storage tank (or the house) becomes hot enough to make the mixing valve close, the storage tank can be charged with layering as usual.

The solution can be to manually close the mixing valve for a while until the storage tank have some hot water in the top.

The same phenomenon may occur if you have a separate boiler room with a large main storage tank and culvert to a smaller slave tank inside the house. If firing begins and the charging to the slave tank begins, the flow on the culvert might be greater than the flow from the boiler, which will lead to a too low temperature out to the culvert. This may lead to a low, even temperature on the whole system.

On our new regulator Laddomat MR, we’ve added a function to block the first charging sequence for a few minutes. This allows the main tank to be filled with some hot water before charging begins, to prevent this problem.

Are there any benefits of using Laddomat if I don’t have a storage tank?

Even without storage tank, a Laddomat can always be used to protect the boiler from cold return water. See manual for recommended connection.

What’s the benefits of using a storage tank (and Laddomat) when I only have a pellet boiler?

A pellet boiler might have problem keeping the temperature up if a lot of hot water is used at the same time. With a storage tank the hot water volume can be increased and this problem will not occur.

A well insulated storage tank has much lower losses than a boiler (depending on boiler model and age) and the heat losses can be lowered a lot by storing the heat in the storage tank instead of keeping the boiler warm all the time.

Longer run times and less start/stop will increase the effectiveness of the boiler and lower environmental impact as the boiler is allowed to run on optimum output all the time.

What’s the lifetime of the thermostat cartridge in the Laddomat?

Recommended service time is 3 years, but this can vary a lot depending on working conditions in the installation. A thermostat can be worn out in as short as 1-2 years, but 10-15 or even 20 years are not uncommon.

During normal conditions the thermostat won’t stop working completely just like that, but when being worn out, the thermostat will open at a higher and higher temperature.

What can affect the lifetime?

Temperatures close to or over 100°C in combination with pressure shocks at boiling temperature, can shorten lifetime and in rare cases even make the thermostat stop working instantly.

In some installation there can be a “pending” which makes the temperatures vary up and down during firing. This forces the thermostat to open/close many times more than usual. The thermostat can only make a certain amount of start/stop motions, which means it will get worn out a lot faster in these cases.

How do I do if I want to connect a Laddomat with pipes with larger dimension than R32?

We have an adapter kit which simplifies the transition from R32 to R40 or R50. This kit can be ordered in a package of 3 pcs. More info can be found here.

I’ve installed a Laddomat with your new ”high quality” shut-off valves with lever, but the valves are leaking from the spindle. What do I do?

Our lever ball valves have a sealing box around the spindle. If the valve starts to leak, it is a simple matter to remove the lever and tighten the compression nut, which compresses the box further and the leak disappears.

You can even remove the nut and “re-seal”, without draining the system.

All of the seals are constructed from teflon, i.e. there are no rubber seals that can deteriorate or leak. This means that you do not need to replace the valve, even after many years of operation.

Click here for instruction.

How do I reclaim a malfunctioning product from you?

You can contact us for technical advice by E-mail or by phone, but in the end you will have to contact the distributor where you bought the product.

The warranty is valid for 2 years from installation date or 3 years from manufacturing date.

Some parts are normal wear and tear parts and is treated differently.

Is the old pump head, Wilo RS25-6, still available for Laddomat 21?

Yes, the pump head will be available as spare part for Laddomat 21 until 2020. After January 1 st 2020, only pump heads approved according to ErP* 2015 may be sold (inside EU).

* ErP means that all circulation pumps must be more energy efficient. We have pump options approved according to ErP 2015 for all our products.

I ordered a new pump head for my Laddomat 21, but I received a low energy pump, and the pump wheel is very small compared to the old pump. Is that really going to work?

Yes, some models of low energy pumps have a smaller pump wheel. The pumps are running on much higher speed instead.

Why should I use a Laddomat with self-circulation?

Self-circulation gives the chance to fire the boiler – on low output – and be able to get some heat to the accumulator, even when the electricity is out.

The flow capacity on self-circulation is off course a lot lower on self-circulation than with a pump running.

The exact self-circulation capacity is determined by pipe dimension and distance as well as temperature and height difference between boiler and accumulator.

Depending on the output of the boiler, the cooling from self-circulation might be enough to keep the temperature on the boiler down, but the temperature can still go up until the boiler’s safety system kicks in (shutting down the fan, opening a cooling valve to cool the boiler, draught regulator shuts the draught etc.).

What you always have with the self-circulation though, is a safety from “dry boiling”. There will always be water circulating between boiler and accumulator so the boiler can’t run out of water and run dry. Without water the boiler will probably be destroyed and the house might burn down.

I had a power failure and my boiler was over heated, even though I have a Laddomat with self-circulation?

Self-circulation is not a guarantee that the boiler won't become over heated.

Self-circulation gives the chance to fire the boiler – on low output – and be able to get some heat to the accumulator, even when the electricity is out.

The flow capacity on self-circulation is off course a lot lower on self-circulation than with a pump running.

The exact self-circulation capacity is determined by pipe dimension and distance as well as temperature and height difference between boiler and accumulator.

Depending on the output of the boiler, the cooling from self-circulation might be enough to keep the temperature on the boiler down, but the temperature can still go up until the boiler’s safety system kicks in (shutting down the fan, opening a cooling valve to cool the boiler, draught regulator shuts the draught etc.).

What you always have with the self-circulation though, is a safety from “dry boiling”. There will always be water circulating between boiler and accumulator so the boiler can’t run out of water and run dry. Without water the boiler will probably be destroyed and the house might burn down.

Can I use Laddomat without storage tank?

Yes, it's possible to use Laddomat without storage tank. Connection should be done according to this picture.

If Laddomat 21, 21-60, 21-100 or M120 is used, the check valve should be blocked.

What's the benefits from using ErP-pumps?

An ErP approved pump has about half the energy consumption compared to an "old" pump on the same speed.

NOTE! On a Laddomat the automatic speed control can't be used. The pump should always be set to constant flow.

What mixing valves can be used with Thermomatic?

All Thermomatic models will off course fit on our own mixing valves.

The old models like Thermomatic K, CBJ and ERA has some limitations for what type of valves and valve dimensions they fit on.

Attached with Thermomatic EC Home, CC and TVM are standard mounting kits that allows mounting on mixing valves typ ESBE VRG/VRB as well as mixing valves of the same type as our own mixning valves, which means the most common mixing valves with 90° turning angle.

For other mixing valve types with 90° turning angle, special mounting kits can be ordered.